Act 1866. These acts were repealed and a new act passed, the Bills of

Sale Act 1878, which, in the main, followed the lines of the act of 1854. The scope of this legislation was very much widened by the Bills of Sale Act (1878) Amendment Act 1882, which was intended primarily "to prevent needy persons being entrapped into signing complicated documents which they might often be unable to comprehend, and so being subjected by their creditors to the enforcement of harsh and unreasonable provisions" (_Manchester &c. Ry. Co._ v. _N.C. Wagon Co._, 1888, 13 App. Ca. 554). The law is now regulated by these two acts, together with the Bills of Sale Acts of 1890 and 1891, which effected further small amendments by excluding from the operation of the principal acts instruments hypothecating, charging or declaring trusts on imported goods, during the interval between their unloading from a ship and their deposit in a warehouse, or re-shipping.

Under the acts of 1878 and 1882 bills of sale are of two kinds, _i.e. absolute bills of sale_ (where chattels are sold absolutely to a purchaser), and _bills of sale by way of security for the payment of money_. The Bills of Sale Act 1878 governs both kinds and is the only act which applies to absolute bills. Bills of sale given by way of security for the payment of money on or after the 1st of November 1882 are governed by the act of 1882, which, however, does not apply to absolute bills. Section 4 of the act of 1878 defines a bill of sale as (1) including bills of sale, assignments, transfers, declarations of trust without transfer, inventories of goods with receipt thereto attached, or receipts for purchase moneys of goods and other assurances of personal chattels; the term assurance has been best explained as a document "on which the title of the transferee of the goods depends, either as the actual transfer of the property, or an agreement to transfer," _Marsden_ v. _Meadows_, 1881, 7 Q.B.D. 80; (2) powers of attorney, authorities or licences to take possession of personal chattels as security for any debt; these words would not include a power of distress for rent in an ordinary lease or bona fide hiring or hire purchase agreements; (3) any agreement, whether intended or not to be followed by the execution of any other instrument, by which a right in equity to any personal chattels, or to any charge or security thereon, shall be conferred; (4) any mode of disposition of trade machinery and attornments and other instruments giving powers of distress to secure a debt or advance. On the other hand, certain assurances and instruments are expressly exempt by statute from the definition: marriage settlements, assignments of ships, assignments for the benefit of creditors, bills of lading and dock warrants, and by the act of 1882, debentures and debenture stock of a company. The expression "personal chattels" is defined as goods, furniture and other articles capable of complete transfer by delivery, and (when separately assigned or charged) fixtures and growing crops.

_Absolute Bills._--Absolute bills of sale must be duly attested by a solicitor, and the attestation must state that before execution the effect of it was explained to the grantor by the attesting solicitor. The consideration must be truly stated. The bill of sale, and all schedules and inventories annexed to or referred to in the bill, and also a true copy of the bill and of every schedule and inventory and of every attestation, together with an affidavit stating the time of making or giving the bill, its due execution and attestation and the residence and occupation of the grantor, and every attesting witness, must be presented to, and the copies filed by, the registrar within seven clear days. In the case of absolute bills the effect of non-compliance does not affect the validity of the bill as between the parties to it, but makes it void as against the trustee in bankruptcy and execution creditors of the grantor.

_Bills by Way of Security._--All bills of sale given by way of security for the repayment of money must be made in accordance with the form given in the schedule to the act of 1882, and they must not depart from the statutory form in anything which is not merely a matter of verbal difference. The form given in the schedule to the act is as follows:--

This Indenture made the ___ day of ___ between A. B. of ___ of the one part and C. D. of ___ of the other part, witnesseth that in consideration of the sum of L ___ now paid to A. B. by C. D, the receipt of which the said A. B. hereby acknowledges, he the said A. B. doth hereby assign unto C. D. his executors, administrators and assigns all and singular the several chattels and things specifically described in the schedule hereto annexed by way of security for the payment of the sum of L ___ and interest thereon at the rate of ___ % per annum. And the said A. B. doth further agree and declare that he will duly pay to the said C. D. the principal sum aforesaid together with the interest then due, by equal ___ payments of L ___ on the ___ day of ___ And the said A. B. doth also agree with the said C. D. that he will (_here insert terms as to insurance, payment of rent, &c., which the parties may agree to for the maintenance or defeasance of the security_). Provided always that the chattels hereby assigned shall not be liable to seizure or to be taken possession of by the said C. D. for any cause other than those specified in Sec. 7 of the Bills of Sale Act (1878) Amendment Act 1882.

In witness, &c.

Signed and sealed by the said A. B. in the presence of me E. F. (_add witness's name, address and description_).

Non-compliance with the requirement of the statute as to form renders a bill of sale void even as between the parties. The bill of sale must have annexed to it an inventory of the chattels comprised in it, and is void, except as against the grantor, in respect of any personal chattels not specifically described. It must be duly attested by one or more credible witnesses (not necessarily by a solicitor, as in the case of absolute bills). Every witness must sign his name and add his address and description. It must be duly registered within seven clear days after the execution thereof, or if it is executed in any place out of England then within seven clear days after the time at which it would in the ordinary course of post arrive in England if posted immediately after the execution. It must truly set forth the consideration. The grantor must be the true owner of the goods described in the schedule; as to any personal chattels of which he is not the true owner, the bill is void, except as against the grantor. Every bill of sale made or given in consideration of any sum under L30 is void. By Sec. 7 of the act personal chattels shall only be liable to be seized or taken possession of in the following cases:--(1) If the grantor make default in payment of the debt or in the performance of any covenant or agreement contained in the bill and necessary for maintaining the security; (2) if the grantor becomes a bankrupt or suffers the goods to be distrained for rent, rates or taxes; (3) if the grantor fraudulently removes the goods from the premises; (4) if the grantor does not, without reasonable excuse, upon demand in writing by the grantee, produce to him his last receipts for rent, rates or taxes; (5) if execution is levied against the goods of the grantor under any judgment. By Sec. 13 personal chattels seized or taken possession of under a bill must not be removed or sold until after the expiration of five clear days from the date of seizure, and, if the goods have been wrongly seized, the grantor may within the five days apply to the High Court or a judge in chambers for an order to restrain the grantee from removing or selling the goods. The Bills of Sale Acts 1878 and 1882 do not apply to Scotland or Ireland. According to Scots law no security or charge can be created over moveable property without delivery of possession. The Irish statutes corresponding to the English acts are the Bills of Sale (Ireland) Act 1879 and the Amendment Act 1883.

The stamp duties payable on an absolute bill of sale are 2s. 6d. on every L25 secured up to L300; over L300, 5s. on every L50. On bills of sale by way of security, 1s. 3d. for every L50 up to L300 secured; over L300, 2s. 6d. for every L100. The fees payable on filing a bill of sale are, 5s. where the consideration (including further advances) does not exceed L100; above L100 and not exceeding L200, 10s.; above L200, L1.

The various trade protection papers always publish the registration of a bill of sale, and the usual effect is, therefore, to destroy the credit of any person giving one. (T. A. I.)

BILLROTH, ALBERT CHRISTIAN THEODOR (1829-1894), Viennese surgeon, was born on the 26th of April 1829 at Bergen, on the island of Ruegen, his family being of Swedish origin. He studied at the universities of Greifswald, Goettingen and Berlin, and after taking his doctor's degree at the last in 1852, started on an educational tour, in the course of which he visited the medical schools of Vienna, Prague, Paris, Edinburgh and London. On his return to Berlin he acted as assistant to B.R.K. Langenbeck from 1853 to 1860, and then accepted the professorship of surgery at Zuerich. In 1867 he was invited to fill the same position at Vienna, and in that city the remainder of his professional life was spent. In 1887 he received the distinction, rarely bestowed on members of his profession, of a seat in the Austrian _Herrnhaus_. He died at Abbazia, on the Adriatic, where he had a beautiful villa, on the 6th of February 1894. Billroth was one of the most distinguished surgeons of his day. His boldness as an operator was only equalled by his skill and resourcefulness; no accident or emergency could disturb his coolness and presence of mind, and his ability to invent or carry out any new procedure that might be demanded in the particular case with which he was dealing, gained for him the appellation of "surgeon of great initiatives." At the same time he was full of consideration for the comfort and well-being of his patient, and never forgot that he had before him a human being to be relieved, not a mere "case" for the display of technical dexterity. He was especially interested in military surgery, and during the Franco-German War volunteered to serve in the hospitals of Mannheim and Weissenburg. His efforts did much to improve the arrangements for the transport and treatment of the wounded in war, and in a famous speech on the War Budget in 1891, he eloquently urged the necessity for an improved ambulance system, pointing out that the use of smokeless powder and the greater precision of the arms of modern warfare must tend to increase the number of men wounded, and that therefore more efficient means must be provided for removing them from the battlefield. Possessing a clear and graceful style, he was the author of numerous papers and books on medical subjects; his _Allgemeine chirurgische Pathologie und Therapie_ (1863) ran through many editions, and was translated into many languages. He was of an exceedingly artistic disposition, and in particular was devoted to music. A good performer on the pianoforte and violin, he was an intimate friend and admirer of Brahms, many of whose compositions were privately performed at his house before they were published. His work on the physiology of music (_Wer ist musikalisch?_) was published after his death.

BILMA, or KAWAR, an oasis in the heart of the Sahara desert, some 60 m. long by 10 broad. The inhabitants are Tibbu and Kanuri. The name Bilma is properly confined to the southern part of this region, where is the chief settlement, called Bilma or Garu. This place is 800 m. due S. of the town of Tripoli and about 350 N. of the N.W. corner of Lake Chad. In the vicinity are a number of lakes, the waters of which on evaporation yield large quantities of very pure and fine salt, which is the object of an extensive trade with the countries of Central Africa. North of Bilma is the town of Dirki, said to date from the 11th century. Near Bilma is a small circular oasis, kept green by a fine spring, but immediately to the south begins the most dreary part of the Saharan desert, over which the caravans travel for fifteen days without discovering the slightest trace of vegetable life. Gustav Nachtigal, who visited Bilma in 1870, records that the temperature during the day rarely sank below 113 deg. Fahr. By the Anglo-French Declaration of the 21st of March 1899 Bilma was included in the French sphere of influence in West Africa. Turkey claimed the oasis as part of the hinterland of Tripoli and garrisoned Bilma in 1902. In 1906, however, a French force from Zinder occupied the town, no opposition being offered by the Ottoman authorities. In 1907 the oasis and surrounding district was created a circle of the Military Territory of the Niger (see SAHARA).

BILNEY, THOMAS (d. 1531), English martyr, was born at or near Norwich. The exact date of his birth is uncertain, but at all events it was not before 1495. He was educated at Trinity Hall, Cambridge, graduating LL.B. and taking holy orders in 1519. Finding no satisfaction in the mechanical system of the schoolmen, he turned his attention to the edition of the New Testament published by Erasmus in 1516. "Immediately," he records, "I felt a marvellous comfort and quietness." The Scriptures now became his chief study, and his influence led other young Cambridge men to think along the same lines. Among his friends were Matthew Parker, the future archbishop of Canterbury, and Hugh Latimer. Latimer, previously a strenuous conservative, was completely won over, and a warm friendship sprang up between him and Bilney. "By his confession," said Latimer, "I learned more than in twenty years before." In 1525 Bilney obtained a licence to preach throughout the diocese of Ely. He denounced saint and relic worship, together with pilgrimages to Walsingham and Canterbury, and refused to accept the mediation of the saints. The diocesan authorities raised no objection, for, despite his reforming views in these directions, he was to the last perfectly orthodox on the power of the pope, the sacrifice of the mass, the doctrine of transubstantiation and the authority of the church. But Wolsey took a different view. In 1526 he appears to have summoned Bilney before him. On his taking an oath that he did not hold and would not disseminate the doctrines of Luther, Bilney was dismissed. But in the following year serious objection was taken to a series of sermons preached by him in and near London, and he was arrested and imprisoned in the Tower. Arraigned before Wolsey, Warham, archbishop of Canterbury, and several bishops in the chapter-house at Westminster, he was convicted of heresy, sentence being deferred while efforts were made to induce him to recant, which eventually he did. After being kept for more than a year in the Tower, he was released in 1529, and went back to Cambridge. Here he was overcome with remorse for his apostasy, and after two years determined to preach again what he had held to be the truth. The churches being no longer open to him, he preached openly in the fields, finally arriving in Norwich, where the bishop, Richard Nix, caused him to be arrested. Articles were drawn up against him by Convocation, he was tried, degraded from his orders and handed over to the civil authorities to be burned. The sentence was carried out in London on the 19th of August 1531. A parliamentary inquiry was threatened into this case, not because parliament approved of Bilney's doctrine but because it was alleged that Bilney's execution had been obtained by the ecclesiastics without the proper authorization by the state. In 1534 Bishop Nix was condemned on this charge to the confiscation of his property. The significance of Bilney's execution lies in the fact that on essential points he was an orthodox Roman Catholic.

See _Letters and Papers of Henry VIII._ vols. iv.-v.; Foxe's _Acts and Monuments_; Gairdner's _History of the Church_; Pollard's _Henry VIII_. (A. F. P.)

BILOXI, a city of Harrison county, Mississippi, U.S.A., in the south part of the state, on Biloxi Bay, a branch of the Mississippi Sound, which is a part of the Gulf of Mexico. By rail it is 80 m. N.E. of New Orleans and 61 m. S.E. of Mobile, Alabama. Pop. (1880) 1540; (1890) 3234; (1900) 5467 (949 being negroes and 455 foreign-born); (1910) 7988. The city is served by a branch of the Louisville & Nashville railway, and by an electric railway extending to Bay St Louis, through Gulfport (pop., 1900, 1060; 1910, 6386), 13 m. S.W., the port of entry of the Pearl River customs district, whose exports, chiefly timber, lumber, naval stores and charcoal, were valued at $8,392,271 in 1907. Biloxi is both a summer and a winter resort, particularly for the people of New Orleans and Mobile, and has a fine beach, extending for about 12 m. around its peninsula, and bordered by an automobile drive; along the beach are some attractive residences, hotels and boarding houses, and several sanatoriums. The city's principal industries are the canning of oysters, shrimp, fish, figs and vegetables, and the manufacture of fertilizers and flour. A beautiful thin faience with remarkable metallic glazes is made here. The municipality owns the water-works, the water being obtained from artesian wells. Pierre le Moyne d'Iberville (1661-1706) in 1699 built Fort Maurepas across the bay from the present city; and the settlement there, called Biloxi after the Biloxi Indians, was the first to be established by the French in this region. In 1702 this post, known as Old Biloxi, was abandoned, and the seat of government was removed to the Mobile river. In 1712 a settlement was made on the present site, being the first permanent settlement within what is now the state of Mississippi. Many of the early settlers were French Canadians, who came down the Mississippi to join the new colony. Biloxi was again the capital from 1719 until 1722. It was incorporated as a village in 1872, and was chartered as a city in 1896.

BILSTON, a market town of Staffordshire, England, 21/2 m. S.E. of Wolverhampton and 124 N.W. of London, in the Black Country. Pop. of urban district (1901) 24,034. It is served by the Great Western railway, and by the London & North-Western at Ettingshall Road station. In the vicinity are very productive mines of coal and ironstone, as well as sand of fine quality for casting, and grinding-stones for cutlers. Bilston contains numerous furnaces, forges, rolling and slitting mills for the preparation of iron, and a great variety of factories for japanned and painted goods, brass-work and heavy iron goods. Though retaining no relics of antiquity, the town is very ancient, appearing in Domesday. The parish church of St Leonard, dating as it stands mainly from 1827, is on the site of a building of the 13th century. Bilston suffered severely from an outbreak of cholera in 1832. The town is within the parliamentary borough of Wolverhampton.

BILTONG, a South African Dutch word (from _bil_, buttock, and _tong_, tongue), for sun-dried strips of antelope or buffalo meat.

BIMANA (Lat. "two-handed"), a word first used by the naturalist Johann Friedrich Blumenbach to distinguish the order of man from Quadrumana or other mammals. The term was popularized by Cuvier, and the majority of writers followed him in its adoption. In 1863, however, Huxley in his _Man's Place in Nature_ demonstrated that the higher apes might fairly be included in Bimana. Again and again it has been proved that the human great toe can be by constant practice used as a thumb; artists exist who have painted pictures grasping the brush with their toes, and violinists have been known to play their instruments in the same manner. Among many savage races there is developed a remarkable power of foot-grasp, which in a lesser degree is often so noticeable among sailors. Haeckel calls attention to the fact that a baby can hold a spoon with the big-toe as with a thumb. Man, in a word, is potentially quadrumanous.

BIMETALLISM. The very general employment of both gold and silver for currency purposes (see MONEY) has given rise to serious practical difficulties which have in turn led to keen theoretical discussion as to the proper remedies to be employed. Though every arrangement under which two metals form the money of a region may be described as "bimetallism," the term--as often happens in economics--has received a specialized meaning. It denotes a system under which the two metals are freely received by the mint and are equally available as legal tender. The last clause implies the establishment of a definite ratio in value between the two metals (e.g. 1 oz. of gold = 151/2 oz. of silver) so that the title "rated bimetallism" may be given to it, in contradistinction to the "unrated bimetallism" which exists wherever two metals circulate together, but have their relative values determined, not by law, but by "the higgling of the market." Further, the inventor of the term--H. Cernuschi in 1869--regarded it as properly applicable to an international arrangement by which a number of states agree to adopt the same ratio, rather than to the use of the two metals by a single country, which may be described as national bimetallism. International bimetallism is at all events the form which has attracted attention in recent times, and it is certainly the most important.

Regarded from the historical point of view it appears that the failure of separate countries to maintain the two metals in circulation was the cause which produced the idea of bimetallism as an international system. We find first the upholders of a national double standard, as in France and the United States, and these are followed by the advocates of bimetallism set up by a combination of countries. The theoretical considerations which underlie the controversy between the supporters and the opponents of bimetallism find their appropriate place in the article MONEY, as does also the earlier history of the double standard. The circumstances that have led to the prominence of the bimetallic question and the principal events that have marked the course of the movement form the subject of this article.

In the earlier years of the 19th century, when the monetary disturbances that resulted from the Revolutionary wars had ceased, we find France (1803) and the United States (1792) with the double standard legally established. England, on the other hand, had in 1816 accepted by law the _gold standard_, which had come into use in the 18th century. Silver formed the currency of the other European countries. The great discoveries of gold in California (1848) and Australia (1851) brought about the displacement of silver by gold in France, and the continuance of gold as the principal currency metal in the United States, where by the law of 1834 it had been somewhat over-rated (1:16), as compared with the ratio adopted in France (1:151/2), and had therefore expelled most of the silver previously in circulation. Between 1848 and 1860 over L100,000,000 of gold was coined in France, while an equivalent amount of silver was exported, principally to the East.

At this time the weight of economic and official opinion was very decidedly in favour of the single gold standard as the best system. In 1865 the Latin Union was established, in which the French currency system was adopted and was followed by the international conference of 1867 in Paris (see MONETARY CONFERENCES), when gold was unanimously accepted as the standard for the proposed international system to be produced by coordinating the various currencies with that of the Latin Union.

A series of political and economic events speedily changed this situation. The Franco-German War (1870-71) deposed France from her leading position, and led to the establishment of a German gold currency with a different unit from the franc, accompanied by the demonetization of the silver currencies previously in use in the German states. The United States, where an inconvertible paper currency had been introduced during the Civil War, formally established the gold dollar as the standard coin (1873) and arranged for a return to specie payments (1878). At this time, too, the great production of gold which had marked the period 1850-1870 diminished, while very productive silver mines were discovered in the Pacific states of America. As a result of these combined influences the gold price of silver, which had risen a little during the height of the gold discoveries, began to fall rapidly, and the reverse process to that by which France had in the 'fifties acquired a gold currency came into operation. Silver, in accordance with _Gresham's Law_, was imported and offered for coinage. To obviate this the policy of limiting the coinage of silver (the _Limping Standard_) was adopted by the Latin Union. A further fall in the gold price of silver naturally resulted, and this made the position of Eastern trade and the finances of the Indian government insecure. American silver producers, and the German government, as holders of a large mass of demonetized silver, were also sufferers by the depreciation. The effect on public and official opinion was shown by the English parliamentary committee on the depreciation of silver (1876), the American silver commission of the same year, and the appearance of many works on the subject, most of them advocating the double standard. On the initiative of the United States an international monetary conference met in Paris in 1878, but though the necessity of keeping a place for silver in the money of the world was recognized, the proposal to adopt the double standard for general use was rejected by the European states. By the Bland-Allison Act (Feb. 1878) the United States had provided for the coinage of a certain amount of silver per month as a mode of keeping up the price of the metal, which notwithstanding fell to 48 pence per oz. in 1879. The prolonged depression of trade in America and Germany was attributed to the scarcity of money, due to what was described as "the outlawry of silver." By the joint action of France and the United States a fresh monetary conference was held in Paris in 1881, where the advocates of bimetallism were very strongly represented. After prolonged discussion no conclusion was reached, in consequence of the refusal of England and Germany to abandon the gold standard. Though an adjournment to the following year was resolved on, the conference did not reassemble, and the bimetallic movement took the form of agitation, carried on in each country. The English inquiry into the depression of trade (1885-1886) drew from the commission a recommendation for a fresh commission to investigate the relation of gold and silver. This latter body, appointed in 1886, obtained a great body of important evidence, and in 1888 closed its work by a report in which the views of the two sections of the commission were separately presented. Six members supported the existing gold standard and six were in favour of the bimetallic system. This inconclusive result was soon followed in the United States by the Sherman Act (1890), providing for a larger monthly coinage of silver. A temporary rise in the price of the metal was followed by a further fall, making the situation still more critical. A new monetary conference was summoned by the United States and met in Brussels in November 1892. To modify opposition the "desirability of increasing the use of silver" was the resolution proposed; the actual method being left open. This conference also proved abortive and adjourned to 1893, but like that of 1881 did not meet again.

International action having failed to secure any system of bimetallism, the United States and India sought to relieve their position by local legislation. The former repealed the Sherman Act, and the latter closed its mints to the free coinage of silver (1893). As these measures were opposed to bimetallism in that they restricted the use of silver, and were followed by a lower price for that metal than had ever been known, the agitation in the United States and Europe continued. In America it took the form of advocating the free coinage of silver by the United States without waiting for other countries; and in this shape made the principal issue at the presidential elections of 1896 and 1900, in each of which it was emphatically rejected.

A further attempt at securing international bimetallism was made by Senator Wolcott's commission in 1897. The American envoys, in concert with the French government, proposed to England (1) the reopening of the Indian mints, and (2) the annual purchase by England of L10,000,000 of silver. The French minister claimed further concessions which were regarded as inadmissible by the English government; but the fate of the mission was settled by the refusal of the Indian government to reopen its mints.

After the American election of 1900, bimetallism as a popular cause disappeared from view. The silver issue was withdrawn from the democratic platform in 1904, and the bimetallic movement died out in England.

Amongst the causes of this collapse the most important are: (1) the adoption of the gold standard by so many countries--Austria-Hungary (1892), Russia and Japan (1897), India (1899), Mexico (1904)-a movement which pointed to the complete triumph of gold in the future; (2) the great increase in the output of gold. Australia and South Africa so developed their gold mines as to bring the yield for 1906 to L81,000,000 as contrasted with the less than L20,000,000 of 1883. This growing supply removed all that dread of a "gold famine" which served as a popular argument with bimetallists. To these may be added (3) the knowledge that experience had brought of the difficulties surrounding any attempt to establish a common ratio where the interests of different countries are so opposed; and (4) the great expansion of trade and industry, concomitantly with the wider adoption of the gold standard. Therefore, to quote the words of perhaps the ablest advocate of bimetallism, "The outcome of the prolonged controversy ... appears to be that the commercial world will carry on its business principally and more and more on a gold basis, and that particular countries will endeavour in different ways to adjust their actual medium ... to the gold standard" (Nicholson, _Money and Monetary Problems_, 6th ed.).

Perhaps the principal service rendered by the many able minds engaged in the movement will prove to be the fuller development of the more difficult parts of monetary theory and the additional light thrown on the course of monetary history.

A proposal, sometimes confounded with bimetallism, is that for a standard composed of both gold and silver, which is better described as the _Joint-standard_ or as _Symmetallism_.

BIBLIOGRAPHY.-On the bimetallic side, Nicholson, _Money and Monetary Problems_ (6th ed., 1903); F.A. Walker, _International Bimetallism_ (1896); Barbour, _The Theory of Bimetallism_ (1885); Lord Aldenham (H.H. Gibbs), _A Colloquy on Currency_ (1900); and the numerous pamphlets and leaflets of the Bimetallic League. Opposed to bimetallism, Giffen, _The Case against Bimetallism_ (1892); Laughlin, _History of Bimetallism in the United States_ (4th ed., 1897); Lord Farrer, _Studies in Currency_ (1898), _The Gold Standard_ (1898)--papers issued by the Gold Standard Defence Assoc. Leonard Darwin's _Bimetallism_ aims at a judicial summary. See also MONEY, MONETARY CONFERENCES. (C. F. B.)

BIMLIPATAM, a town of British India, in the Vizagapatam district of Madras, on the sea-coast 18 m. N.E. of Vizagapatam. Pop. (1901) 10,212. It was formerly a Dutch factory, and is now the principal port of the district. The anchorage is an open roadstead protected to some extent by headlands with a lighthouse at Santapalli. Nearly half the sea-borne trade is conducted with foreign countries. The principal exports are oil-seeds, hides and jute.

BIN, a receptacle of various kinds, originally of wicker or basket work. The word appears in most European languages, of. M.L. and Ital. _benna_, Ger. _Benne_, &c.; etymologists trace the word to a root meaning "to plait." It survives in various connexions, e.g. dust-bin, wine-bin (for holding bottles), hop-bin, coal-bin, corn-bin.

BINAN, a town of the province of La Laguna, Luzon, Philippine Islands, on the W. shore of Laguna de Bay, about 20 m. S.S.E. of Manila. Pop. (1903) 9563. The town is surrounded by an extensive and extremely fertile plain which produces very large quantities of rice as well as a great variety of tropical fruits, and a ready market for these products is found in Manila whither they are shipped by boat. The language is Tagalog.

BINARY SYSTEM, in astronomy, a system composed of two stars revolving around each other under the influence of their mutual attraction. A distinction was formerly made between double stars of which the components were in revolution around each other, and those in which no relative motion was observed; but it is now considered that all double stars must really be binary systems.

BINCHOIS, EGIDIUS (d. 1460), an early 15th-century musical composer evidently named after his birthplace, Binche, near Mons. He was esteemed by contemporary and later theorists as second only to Dunstable and Dufay.

BINGEN (anc. _Vincum_ or _Bingium_), a town of Germany, in the grand-duchy of Hesse-Darmstadt, 15 m. N.W. from Mainz, on the main line to Cologne. Pop. (1905) 9950. It is situated on the left bank of the Rhine opposite Ruedesheim, at the confluence of the Nahe (or Nava), which is crossed near its mouth by a stone bridge, attributed to Drusus, and certainly of Roman origin, and an iron railway bridge. On a height immediately to the south-east is the ruined castle of Klopp, on the site of a fortress founded by Drusus, and higher still the celebrated chapel of St Roch (rebuilt in 1895 after a fire), where thousands of pilgrims gather on the first Sunday after the 16th of August. Apart from its situation, which renders it a convenient place of tourist resort, the town itself presents but few attractions. There are a Protestant and three Roman Catholic churches, among the latter the parish church with a crypt dating from the 11th century, and a medieval town hall. It has a considerable commerce in wine, grain and cattle, and, new quays and a harbour having been recently constructed, does an extensive transit trade in coal and iron. A short way down the Rhine is the Bingerloch, a famous whirlpool, while about halfway between it and the town rises on a rock in the middle of the stream the _Maeuseturm_ (derived from _Muserie_, cannon), in which, according to legend, Archbishop Hatto II. of Mainz was in 969 eaten by mice (the legend being doubtless due to the erroneous derivation from _Maeuse_, mice). Another legend states that the Nibelung treasure is hidden hereabouts in the Rhine.

BINGERBRUeCK, a town of Germany, in the Prussian Rhine province, at the confluence of the Nahe and the Rhine, lying just below Bingen, and at the junction of the main lines of railway--Mainz-Coblenz and Bingerbrueck-Metz. It has an extensive trade in the wines of the district. Pop. 2500.

BINGHAM, JOSEPH (1668-1723), English scholar and divine, was born at Wakefield in Yorkshire in September 1668. He was educated at University College, Oxford, of which he was made fellow in 1689 and tutor in 1691. A sermon preached by him from the university pulpit, St Mary's, on the meaning of the terms "Person" and "Substance" in the Fathers, brought upon him a most unjust accusation of heresy. He was compelled to give up his fellowship and leave the university; but he was immediately presented by Dr John Radcliffe to the rectory of Headbournworthy, near Winchester (1695). In this country retirement he began his laborious and valuable work entitled _Origines Ecclesiasticae_, or Antiquities of the Christian Church, the first volume of which appeared in 1708 and the tenth and last in 1722. His design, learnedly, exhaustively and impartially executed, was "to give such a methodical account of the antiquities of the Christian Church as others have done of the Greek and Roman and Jewish antiquities, by reducing the ancient customs, usages and practices of the church under certain proper heads, whereby the reader may take a view at once of any particular usage or custom of Christians for four or five centuries." Notwithstanding his learning and merit, Bingham received no higher preferment than that of Headbournworthy till 1712, when he was collated to the rectory of Havant, near Portsmouth, by Sir Jonathan Trelawney, bishop of Winchester. Nearly all his little property was lost in the great South Sea Bubble of 1720. He died on the 17th of August 1723.

BINGHAMTON, a city and the county-seat of Broome county, New York, U.S.A., in the south part of the state, on both banks of the north branch of the Susquehanna river, at the mouth of the Chenango river. Pop. (1880) 17,317; (1890) 35,005; (1900) 39,647, of whom 4272 were foreign-born; (1910), 48,443. It is an important railway centre, being served by the Delaware & Hudson, the Erie, and the Delaware, Lackawanna & Western railways; and an extensive system of electric railways connects it with the suburbs and neighbouring towns. Binghamton is picturesquely situated and has a number of parks, the most attractive of which are Ross Park of 100 acres, and Ely Park of 134 acres. Among the principal buildings are the city hall, the court-house, the post-office, the Binghamton city hospital, Stone opera-house, the Carnegie library (1904), the central high school, and a state armoury. Binghamton has also some fine office buildings. Among the city's educational and charitable institutions are the Lady Jane Grey school (for girls), St Joseph's academy, St Mary's home for orphans, the Susquehanna Valley orphan asylum, and a state hospital for the insane. Binghamton is a manufacturing centre of considerable importance, ranking twelfth in the state in 1905 in the value of factory products, $13,907,403, which was an increase of 32.0% over the value of the factory products in 1900; among its manufactures are tobacco, cigars, chewing tobacco and snuff (value in 1905, $2,879,217), patent medicines (value in 1905, $2,133,198), flour and grist mill products ($1,089,910), men's clothing ($833,835), and, of less importance, commercial and computing scales and time recorders, chemicals, distilled liquor, beer, fire-alarm apparatus, overalls, agricultural implements, wagons, electrical apparatus, refined oil, sheet metal, paper bags and envelopes, tacks and nails, window glass, glass-ware, clocks, whips and furniture (especially Morris chairs). In the village of Lestershire (pop. in 1910, 3775; incorporated in 1892), about 2 m. west, and in Endicott, another suburb, are large boot and shoe factories. The municipality owns and operates the water-works. When Binghamton was first settled, about 1787, it was known as Chenango Point. Its site was originally included in the so-called "Bingham Patent," a tract on both sides of the Susquehanna river owned by William Bingham (1751-1804), a Philadelphia merchant, who was a member of the Continental Congress in 1787-1788 and of the United States Senate in 1795-1801, being president _pro tempore_ of the Senate from the 16th of February to the 3rd of March 1797. In 1800 a village was laid out by an agent of Mr Bingham, and was named Binghamton. In 1834 it was incorporated as a village, and in 1867 was chartered as a city.

BINGLEY, a market town in the Otley parliamentary division of the West Riding of Yorkshire, England, on the Aire, 51/2 m. N.W. of Bradford, on the Midland railway. Pop. of urban district (1901) 18,449. The church of All Saints is good Perpendicular, though considerably restored. The large industrial population is engaged principally in the worsted and cotton manufacture. The neighbourhood is populous, but the natural beauty of the Aire valley is not greatly impaired.

BINIOU, or BIGNOU, a species of cornemuse or bagpipe, still in use at the present day in Brittany. The biniou is a primitive kind of bagpipe consisting of a leather bag inflated by means of a short valved insufflation tube or blow-pipe, a chaunter with conical bore furnished with a double reed concealed within the stock or socket (see BAG-PIPE), and seven holes, the first being duplicated to accommodate left- and right-handed players.

The scale of the biniou is usually [Illustration][1] and the single drone is tuned to the lower octave of the first hole [Illustration].

The more primitive biniou, still occasionally found in the remote districts of Cornouailles and Morbihan, has a chaunter with but five holes,[2] giving part of the scale of D, the drone being also tuned to D. The drone of the biniou is of boxwood, handsomely inlaid with tin, and has a single or beating reed hidden within the stock.

The word biniou or bignou (a Gallicized form), often erroneously derived from _bigno, se renfler beaucoup_--an etymology not supported by Breton dictionaries--is the Breton plural form of _benvek_, instrument, tool, _i.e. binviou, binvijou_.[3] The word is also found in the phrase, "_Sac'h ar biniou_" (a biniou bag), a bag used by weavers to hold their tools, spindles, &c. The biniou is still the traditional and popular instrument of the Breton peasants of Cornouailles and Morbihan, and is almost inseparable from the bombard (q.v.), which is no other than a survival of the medieval musette, hautbois or chalemie, formerly associated with the bag-pipe in western Europe (see OBOE). At all festivals, at the _pardons_, wedding feasts and threshing dances, the two traditional musicians or _sonneurs_ give out in shrill penetrating tones the ancient Breton _rondes_[4] and melodies.

FOOTNOTES:

[1] See Victor Mahillon, _Catalogue descriptif_, vol. ii. (Ghent, 1896), p. 353, No. 1126; and Captain C.R. Day, _Descriptive Catalogue of Musical Instruments_ (London, 1891), p. 62, No. 135.

[2] See N. Quellien, _Chansons et danses des Bretons_ (Paris, 1889), p. 39, and note, where the description of the instrument is not technical.

[3] See Le Gonidec, _Dictionnaire breton-francais_, ed. by T. Hersart de la Villemarque; and N. Quellien, _op. cit_. p. 37, note.

[4] For examples of these see N. Quellien, _op. cit_. part ii.

BINMALEY, a town of the province of Pangasinan, Luzon, Philippine Islands, on the delta of the Agno river, about 5 m. W. of Dagupan, the north terminus of the Manila & Dagupan railway. Pop. (1903) 16,439. It has important fisheries, and manufactures salt, pottery, roofing (made of nipa leaves), and nipa wine. Rice and cocoanuts are the principal agricultural products of the town.

BINNACLE (before 18th century _bittacle_, through Span. _bitacula_, from Lat. _habitaculum_, a little dwelling), a case on the deck of a ship, generally in front of the steersman, in which is kept a compass, and a light by which the compass is read at night.

BINNEY, EDWARD WILLIAM (1812-1881), English geologist, was born at Morton, in Nottinghamshire, in 1812. He was articled to a solicitor in Chesterfield, and in 1836 settled at Manchester. He retired soon afterwards from legal practice and gave his chief attention to geological pursuits. He assisted in 1838 in founding the Manchester Geological Society, of which he was then chosen one of the honorary secretaries; he was elected president in 1857, and again in 1865. He was also successively secretary and president of the Literary and Philosophical Society of Manchester. Working especially at the Carboniferous and Permian rocks of the north of England, he studied also the Drift deposits of Lancashire, and made himself familiar with the geology of the country around Manchester. On the Coal Measures in particular he became an acknowledged authority, and his _Observations on the Structure of Fossil Plants found in the Carboniferous Strata_ (1868-1875) formed one of the monographs of the Palaeontographical Society. His large collection of fossils was placed in Owens College. He was elected a fellow of the Royal Society in 1856. He died at Manchester on the 19th of December 1881.

BINNEY, HORACE (1780-1875), American lawyer, was born in Philadelphia, Pennsylvania, on the 4th of January 1780. He graduated at Harvard College in 1797, and studied law in the office of Jared Ingersoll (1749-1822), who had been a member of the Constitutional convention of 1787, and who from 1791 to 1800 and again from 1811 to 1816 was the attorney-general of Pennsylvania. Admitted to the bar in Philadelphia in 1800, Binney practised with great success for half a century, and was recognized as one of the leaders of the bar in the United States. He served in the Pennsylvania legislature in 1806-1807, and was a Whig member of the National House of Representatives from 1833 until 1835, ably defending the United States Bank, and in general opposing the policy of President Andrew Jackson. His most famous case, in which he was unsuccessfully opposed by Daniel Webster, was the case of _Bidal v. Girard's Executors_, which involved the disposition of the fortune of Stephen Girard (q.v.). Binney's argument in this case greatly influenced the interpretation of the law of charities. Binney made many public addresses, the most noteworthy of which, entitled _Life and Character of Chief Justice Marshall_, was published in 1835. He also published _Leaders of the Old Bar of Philadelphia_ (1858), and an _Inquiry into the Formation of Washington's Farewell Address_ (1859); and during the Civil War he issued three pamphlets (1861, 1862 and 1865), discussing the right of _habeas corpus_ under the American Constitution, and justifying President Lincoln in his suspension of the writ.

See the _Life of Horace Binney_ (Philadelphia, 1904), by his grandson, C.C. Binney.

BINNEY, THOMAS (1798-1874), English Congregationalist divine, was born of Presbyterian parents at Newcastle-on-Tyne in 1798, and educated at an ordinary day school. After spending seven years in the employment of a bookseller he entered the theological school at Wymondley, Herts, now incorporated in New College, Hampstead. In 1829, after short pastorates at Bedford (New Meeting) and Newport, Isle of Wight, he accepted a call to the historic Weigh House chapel, London. Here he became very popular, and it was found necessary to build a much larger chapel on Fish Street Hill, to which the congregation removed in 1834. An address delivered on the occasion of the laying of the foundation stone was published, with an appendix containing a strong attack on the influence of the Church of England, which gave rise to a long and bitter controversy. Throughout his whole career Binney was a vigorous opponent of the state church principle, but those who simply classified him as a narrow-minded political dissenter did him injustice. His liberality of view and breadth of ecclesiastical sympathy entitle him to rank on questions of Nonconformity among the most distinguished of the school of Richard Baxter; and he maintained friendly relations with many of the dignitaries of the Established Church. He continued to discharge the duties of the ministry until 1869, when he resigned. In 1845 he paid a visit to Canada and the United States, and in 1857-1859 to the Australian colonies. The university of Aberdeen conferred the LL.D. degree on him in 1852, and he was twice chairman of the Congregational Union of England and Wales.

Binney was the pioneer in a much-needed improvement of the forms of service in Nonconformist churches, and gave a special impulse to congregational psalmody by the publication of a book entitled _The Service of Song in the House of the Lord_. Of numerous other works the best-known is his _Is it Possible to Make the Best of Both Worlds?_ an expansion of a lecture delivered to young men in Exeter Hall, which attained a circulation of 30,000 copies within a year of its publication. He wrote much devotional verse, including the well-known hymn "Eternal Light! Eternal Light!" His last sermon was preached in November 1873, and after some months of suffering he died on the 24th of February 1874. Dean Stanley assisted at his funeral service in Abney Park cemetery.

BINOCULAR INSTRUMENT, or briefly BINOCULAR,[1] an apparatus through which objects are viewed with both eyes. In this article only those instruments will be considered in which solid objects or _objects in space_ are viewed; reference should be made to the article STEREOSCOPE for the instruments in which _plane_ representations are offered to both eyes. The natural vision is such that different central projections of the objects are communicated to both eyes; the difference of the two perspective representations arises from the fact that the projection centres are laterally separated by an interval about equal to the distance between the eyes (the inter-pupillary distance). Binocular instruments should aid the natural spatial or stereoscopic vision, or make it possible if the eyes fail. If the objects be so far distant that the two perspectives formed by the naked eye are no more distinguished from each other, recourse may be had to binocular telescopes and range-finders; and if the objects be so small that, in order to observe details on them, we must bring our eyes so close to the objects that they cannot accommodate the images, recourse may be had to binocular microscopes and magnifying glasses.

The construction of binocular instruments dates back over several centuries, and has now been brought to great perfection. The subject of their theory and history has been exhaustively treated by M. von Rohr, _Die binokularen Instrumente_ (Berlin, 1907), the first publication to present a complete account of these instruments.

Telescope.

_Binocular Instruments for Observation only._--The first binocular telescope, consisting of two telescopes placed side by side, was constructed in 1608 by Johann Lipperhey, the inventor of the ordinary or Dutch telescope. The subject was next taken up by the monks. The Capuchin Antonius Maria Schyrlaeus (Schyrl) de Rheita (1597-1660) described in 1645 the construction of double terrestrial telescopes. Greater success attended the efforts of the Capuchin Cherubin d'Orleans, who flourished at about the same time, and constructed large double telescopes of the Dutch type of high magnification, for use in war, and smaller instruments of lower magnification; these instruments were provided with mechanism for adjusting to the interval between the eyes of the observer (fig. 1). After these discoveries the subject received no more attention until the 19th century; no improvements of these instruments are recorded in the literature of the second half of the 18th century.

The re-invention of the Dutch binocular telescope apparently dates from 1823, and is to be assigned to the Viennese optician, Johann Friedrich Voigtlaender (1779-1859); but the credit of having placed these instruments on the market probably belongs to J.P. Lemiere in Paris, who, in 1825, took out a French patent for an improvement of the Dutch double telescope. Lemiere's instruments were furnished with a common focusing arrangement, and the adapting to the inter-pupillary distance was effected by turning the two parallel telescopes round their common axis. The development of this instrument was studied by opticians for the remainder of the first half of the 19th century; the last improvement apparently was made by P.G. Bardou in 1854, and by H. Helmholtz in 1857 when he described the telestereoscope (fig. 2) with telescopic magnification. By utilizing the telescope with prism-inversion, devised in 1851 by Ignazio Porro (1795-1875), A.A. Boulanger succeeded in producing a binocular of an entirely new type in 1859 (fig. 3). But he overlooked the possibility of increasing the distance between the objectives; Camille Nachet introduced this improvement in 1875, but his instruments did not meet with much popularity. This was probably due to the fact that, at this time, the manufacture of the glass for the prisms was too difficult; this was overcome by E. Abbe, after the founding of the glass-works at Jena, who effected, independently of his predecessors, the wider separation of the objectives (fig. 4), and increased it in the telestereoscope (fig. 5), or relief telescope, in a manner nearly approaching to Helmholtz's proposal.

Microscope.

The first binocular microscope was invented by the previously mentioned Father Cherubin, whose instrument consisted of two inverting systems, and consequently gave a totally wrong impression of depth, i.e. depressions appeared as elevations, and vice versa, or, as we must say after Charles Wheatstone, it presented a pseudoscopic impression; this quality, however, was not recognized by the microscopists of the time. The instrument subsequently fell into complete neglect for nearly two centuries, to be revived in 1852 by Charles Wheatstone, who has stated that he had previously studied the problem; the publication of his views in his second great paper "On Binocular Vision,"[2] in the _Phil. Trans._ for 1852, undoubtedly stimulated the investigation of this instrument, which was carried on with zeal and success more especially in England and the United States. In 1853 the American J.L. Riddell (1807-1867) devised his binocular microscope, which contained the essentials of Wheatstone's pseudoscope. F.H. Wenham, another constructor, did not at first succeed in avoiding the pseudoscopic effect, but, by the application of _refracting_ dividing prisms, he subsequently arrived at orthoscopic representations and continued the development of the different methods for producing micro-photographic stereograms; this was effected in the first case by placing a diaphragm over one half of the objective for each exposure, and in the second case by a suitable direction of the illuminating pencil (fig. 6). Of greater benefit, however, for stimulating interest in binocular microscopes, was his invention of _reflecting_ dividing prisms (fig. 7). Other experiments, begun by Powell and Lealand, and developed with greater skill by Wenham, were concerned with the binocular vision of identical images. Such an impression could not possibly be stereoscopic, and these experiments led to the construction of a non-stereoscopic binocular microscope. Of the other workers in this field mention may be made of Alfred Nachet, who in 1853, and subsequently in 1863, brought forward two forms of binocular microscope.

The earliest stages of the development of the binocular microscope had been always confined to those instruments with _one_ objective, in the immediate neighbourhood of which the systems for dividing the pencil were placed. At a later date attempts were made to separate the two halves of the objective by modifying the eye-piece; this led to the construction of stereoscopic eye-pieces, initiated by R.B. Tolles, E. Abbe and A. Prazmowski. Of special importance is the work of Abbe; although, as he himself has stated, his methods accidentally led to the Wenham system, he certainly was far above his predecessors in his theoretical treatment of the problem, and in the perspicuity and clearness of his explanation. To him is also due the re-establishment of the instruments, which Wenham had abandoned by reason of too great technical difficulties (fig. 8). The newest form of the binocular microscope is very similar to the oldest form in which two completely separated tubes were employed. The inventor, H.S. Greenough, employs two systems for setting up the image, in order to avoid the pseudoscopic effect. After experiments in the Zeiss works, the erecting of Porro's prisms simultaneously permitted a convenient adaptation to the eye-distance of the observer.

Simple microscope.

The first binocular magnifying glass or simple microscope (German, _Lupe_) was devised by J.L. Riddell in 1853; in this instrument (fig. 9) the pencil of light is transmitted to the eyes by means of two pairs of parallel mirrors. Of the many different improvements mention may be made of A. Nachet's. H. Westien made use of two Chevalier-Bruecke's simple microscopes with their long working distances in order to form an instrument in which the curvature of the image was not entirely avoided. Mention may also be made of the binoculars of K. Fritzsch (formerly Prokesch) and E. Berger.

_Binocular Instruments for Range-finding._--For measuring purposes binocular telescopes with parallel axes are the only types employed. The measurement is effected by adjoining to the space or interval to be measured some means of measurement defined; for example, by a fixed scale which extends into the space, or by a movable point (_Wandermarke_). This instrument shows a transition to the stereoscope, inasmuch as the scale or means of measurement is not directly observed, but to each eye a plane representation is offered, just as in the stereoscope; the space to be measured, on the other hand, is portrayed in exactly the same way as in the double telescope. The method for superposing the two spaces on one another was deduced by Sir David Brewster in 1856, but he does not appear to have dealt with the problem of range-finding. The problem was attacked in 1861 by A. Rollet; later, in 1866, E. Mach published a promising idea, and finally--independently of the researches of his predecessors--Hektor de Grousilliers, in partnership with the Zeiss firm (E. Abbe and C. Pulfrich), constructed the first stereoscopic range-finder suitable for practical use. (O. Hr.)

FOOTNOTES:

[1] The term binocular (from the Lat. _bini_, two at a time, and _oculi_, eyes) was originally an adjective used to describe things adapted for the simultaneous use of both eyes, as in "binocular vision," "a binocular telescope or microscope"; now "a binocular" is used as a noun, meaning a binocular microscope, a field-glass, &c.

[2] The first part appeared in 1838.

BINOMIAL (from the Lat. _bi-, bis_, twice, and _nomen_, a name or term), in mathematics, a word first introduced by Robert Recorde (1557) to denote a quantity composed of the sum or difference to two terms; as a + b, a - b. The terms trinomial, quadrinomial, multinomial, &c., are applied to expressions composed similarly of three, four or many quantities.

The _binomial theorem_ is a celebrated theorem, originally due to Sir Isaac Newton, by which any power of a binomial can be expressed as a series. In its modern form the theorem, which is true for all values of n, is written as

n.(n-1) (x + a)^n = x^n + nax^(n-1) + ------- a squaredx^(n-2) 1.2

n.(n-1).(n-2) + -------------a cubedx^(n-3) ... + a^n. 1.2.3

The reader is referred to the article ALGEBRA for the proof and applications of this theorem; here we shall only treat of the history of its discovery.

The original form of the theorem was first given in a letter, dated the 13th of June 1676, from Sir Isaac Newton to Henry Oldenburg for communication to Wilhelm G. Leibnitz, although Newton had discovered it some years previously. Newton there states that

m m - n m - 2n (p + pq)^(m/n) = p^(m/n) + -- aq + ----- bq + ------ cq ... &c., n 2n 3n

where p + pq is the quantity whose (m/n)th power or root is required, p the first term of that quantity, and q the quotient of the rest divided by p, m/n the power, which may be a positive or negative integer or a fraction, and a, b, c, &c., the several terms in order, e.g.

m (m - n) a = p^(m/n), b = -- aq, c = ------- bq, and so on. n 2n

In a second letter, dated the 24th of October 1676, to Oldenburg, Newton gave the train of reasoning by which he devised the theorem.

"In the beginning of my mathematical studies, when I was perusing the works of the celebrated Dr Wallis, and considering the series by the interpolation of which he exhibits the area of the circle and hyperbola (for instance, in this series of curves whose common base or axis is x, and the ordinates respectively (1 - xx)^(0/2), (1 - xx)^1/2, (1 - xx)^(2/2), (1 - xx)^(3/2), &c), I perceived that if the areas of the alternate curves, which are x, x - (1/3)x cubed, x - (2/3)x cubed + (1/5)x^5, x - (3/3)x cubed + (3/5)x^5 - (1/7)x^7, &c., could be interpolated, we should obtain the areas of the intermediate ones, the first of which (1 - xx)^{1/2} is the area of the circle. Now in order to [do] this, it appeared that in all the series the first term was x; that the second terms (0/3)x cubed, (1/3)x cubed, (2/3)x cubed, &c., were in arithmetical progression; and consequently that the first two terms of all the series to be interpolated would be

(1/2)x cubed (3/2)x cubed (5/2)x cubed x - -----, x - -------, x - -------, &c. 3 3 3

"Now for the interpolation of the rest, I considered that the denominators 1, 3, 5, &c., were in arithmetical progression; and that therefore only the numerical coefficients of the numerators were to be investigated. But these in the alternate areas, which are given, were the same with the figures of which the several powers of 11 consist, viz., of 11 deg., 11¹, 11 squared, 11 cubed, that is, the first 1; the second, 1, 1; the third, 1, 2, 1,; the fourth 1, 3, 3, 1; and so on. I enquired therefore how, in these series, the rest of the terms may be derived from the first two being given; and I found that by putting m for the second figure or term, the rest should be produced by the continued multiplication of the terms of this series

m - 0 m - 1 m - 2 ----- x ----- x ----- ..., &c ... 1 2 3

This rule I therefore applied to the series to be interpolated. And since, in the series for the circle, the second term was (1/2x cubed)/3, I put m = 1/2.... And hence I found the required area of the circular segment to be

1/2x cubed (1/8)x^5 (1/16)x^7 x - --- - -------- - ---------, &c. ... 3 5 7

And in the same manner might be produced the interpolated areas of other curves; as also the area of the hyperbola and the other alternates in this series (1 + xx)^(0/2), (1 + xx)^1/2, (1 + xx)^(2/2), &c. ... Having proceeded so far, I considered that the terms (1 - xx)^(0/2), (1 - xx)^(2/2), (1 - xx)^(4/2), (1 - xx)^(6/2), &c., that is 1, 1 - x squared, 1 - 2x squared + x^4, 1 - 3x squared + 3x^4, - x^6, &c., might be interpolated in the same manner as the areas generated by them, and for this, nothing more was required than to omit the denominators 1, 3, 5, 7, &c., in the terms expressing the areas; that is, the coefficients of the terms of the quantity to be interpolated (1 - xx)^1/2 or (1 - xx)^(3/2), or generally (1 - xx)^m will be produced by the continued multiplication of this series

m - 1 m - 2 m - 3 m x ----- x ----- x ----- ... &c. 2 3 4

The binomial theorem was thus discovered as a development of John Wallis's investigations in the method of _interpolation_. Newton gave no proof, and it was in the _Ars Conjectandi_ (1713) that James Bernoulli's proof for positive integral values of the exponent was first published, although Bernoulli must have discovered it many years previously. A rigorous demonstration was wanting for many years, Leonhard Euler's proof for negative and fractional values being faulty, and was finally given by Niels Heinrik Abel.

The _multi_- (or _poly_-) _nomial theorem_ has for its object the expansion of any power of a multinomial and was discussed in 1697 by Abraham Demoivre (see COMBINATORIAL ANALYSIS).

REFERENCES.--For the history of the binomial theorem, see John Collins, _Commercium Epistolicum_ (1712); S.P. Rigaud, _The Correspondence of Scientific Men of the 17th Century_ (1841); M. Cantor, _Geschichte der Mathematik_ (1894-1901).

BINTURONG (_Arctictis binturong_), the single species of the viverrine genus _Arctictis_, ranging from Nepal through the Malay Peninsula to Sumatra and Java. This animal, also called the bear-cat, is allied to the palm-civets, or paradoxures, but differs from the rest of the family (_Viverridae_) by its tufted ears and long, bushy, prehensile tail, which is thick at the root and almost equals in length the head and body together (from 28 to 33 inches). The fur is long and coarse, of a dull black hue with a grey wash on the head and fore-limbs. In habits the binturong is nocturnal and arboreal, inhabiting forests, and living on small vertebrates, worms, insects and fruits. It is said to be naturally fierce, but when taken young is easily tamed and becomes gentle and playful.

BINYON, LAURENCE (1869- ), English poet, born at Lancaster on the 10th of August 1869, was educated at St Paul's school, London, and Trinity College, Oxford, where he won the Newdigate prize in 1890 for his _Persephone_. He entered the department of printed books at the British Museum in 1893, and was transferred to the department of prints and drawings in 1895, the _Catalogue of English Drawings in the British Museum_ (1898, &c.) being by him. As a poet he is represented by _Lyric Poems_ (1894), _Poems_ (Oxford, 1895), _London Visions_ (2 vols., 1895-1898), _The Praise of Life_ (1896), _Porphyrion and other Poems_ (1898), _Odes_ (1900), _The Death of Adam_ (1903), _Penthesilea_ (1903), _Dream come true_ (1905), _Paris and Oenone_ (1906), a one-act tragedy, and _Attila_, a poetical drama (1907); as an art critic by monographs on the 17th-century Dutch etchers, on John Crome and John Sell Cotman, contributed to the _Portfolio_, &c. In 1906 he published the first volume of a series of reproductions from William Blake, with a critical introduction.

See also R.A. Streatfeild, _Two Poets of the New Century_ (1901), and W. Archer, _Poets of the Younger Generation_ (1902).

BIO-BIO, a river of southern Chile, rising in the Pino Hachado pass across the Andes, 38 deg. 45' S. lat., and flowing in a general north-westerly direction to the Pacific at Concepcion, where it is 2 m. wide and forms an excellent harbour. It has a total length of about 225 m., nearly one half of which is navigable.

BIO-BIO, an inland province of southern Chile, bounded N., W. and S. respectively by the provinces of Concepcion, Arauco and Malleco, and E. by Argentina. It has an area of 5246 sq. m. of well-wooded and mountainous country, and exports timber to a large extent. The great trunk railway from Santiago S. to Puerto Montt crosses the western part of the province and also connects it with the port of Concepcion. The capital, Los Angeles (est. pop. 7777 in 1902) lies 151/2 m. E. of this railway and is connected with it by a branch line.

BIOGENESIS (from the Gr. [Greek: bios], life, and [Greek: genesis], generation, birth), a biological term for the theory according to which each living organism, however simple, arises by a process of budding, fission, spore-formation of sexual reproduction from a parent organism. Under the heading of ABIOGENESIS (q.v.) is discussed the series of steps by which the modern acceptance of biogenesis and rejection of abiogenesis has been brought about. No biological generalization rests on a wider series of observations, or has been subjected to a more critical scrutiny than that every living organism has come into existence from a living portion or portions of a pre-existing organism. In the articles REPRODUCTION and HEREDITY the details of the relations between parent and offspring are discussed. There remains for treatment here a curious collateral issue of the theory. It is within common observation that parent and offspring are alike: that the new organism resembles that from which it has come into existence: in fine, biogenesis is homogenesis. Every organism takes origin from a parent organism of the same kind. The conception of homogenesis, however, does not imply an absolute similarity between parent and organism. In the first place, the normal life-cycle of plants and animals exhibits what is known as alternation of generations, so that any individual in the chain may resemble its grand-parent and its grand-child, and differ markedly from its parent and child. Next, any organism may pass through a series of free-living larval stages, so that the new organism at first resembles its parent only very remotely, corresponding to an early stage in the life-history of that parent. (See EMBRYOLOGY, LARVAL FORMS and REPRODUCTION.) Finally, the conception of homogenesis does not exclude the differences between parent and offspring that continually occur, forming the material for the slow alteration of stocks in the course of evolution (see VARIATION AND SELECTION). Homogenesis means simply that such organism comes into existence directly from a parent organism of the same race, and hence of the same species, sub-species, genus and so forth.

From time to time there have been observers who have maintained a belief in the opposite theory, to which the name heterogenesis has been given. According to the latter theory, the offspring of a given organism may be utterly different from itself, so that a known animal may give rise to another known animal of a different race, species, genus, or even family, or to a plant, or vice versa. The most extreme cases of this belief is the well-known fable of the "barnacle-geese," an illustrated account of which was printed in an early volume of the Royal Society of London. Buds of a particular tree growing near the sea were described as producing barnacles, and these, falling into the water, were supposed to develop into geese. The whole story was an imaginary embroidery of the facts that barnacles attach themselves to submerged timber and that a species of goose is known as the bernicle goose. In modern times the exponents of heterogenesis have limited themselves to cases of microscopic animals and plants, and in most cases, the observations that they have brought forward have been explained by minuter observation as cases of parasitism. No serious observer, acquainted with modern microscopic technical methods, has been able to confirm the explanation of their observations given by the few modern believers in heterogenesis. (P. C. M.)

BIOGRAPHY (from the Gr. [Greek: bios], life, and [Greek: graphae], writing), that form of history which is applied, not to races or masses of men, but to an individual. The earliest use of the word [Greek: biographia] is attributed to Damascius, a Greek writer of the beginning of the 6th century, and in Latin _biographia_ was used, but in English no earlier employment of the word, "biography" has been traced than that of Dryden in 1683, who uses it to describe the literary work of Plutarch, "the history of particular men's lives." It is obvious that this definition is necessary, for biography is not the record of "life" in general, but of the life of a single person. The idea of the distinction between this and history is a modern thing; we speak of "antique biography," but it is doubtful whether any writer of antiquity, even Plutarch, clearly perceived its possible existence as an independent branch of literature. All of them, and Plutarch certainly, considered the writing of a man's life as an opportunity for celebrating, in his person, certain definite moral qualities. It was in these, and not in the individual characteristics of the man, that his interest as a subject of biography resided.

The true conception of biography, therefore, as the faithful portrait of a soul in its adventures through life, is very modern. We may question whether it existed, save in rare and accidental instances, until the 17th century. The personage described was, in earlier times, treated either from the philosophical or from the historical point of view. In the former case, rhetoric inevitably clouded the definiteness of the picture; the object was to produce a grandiose moral effect, to clothe the subject with all the virtues or with all the vices; to make his career a splendid example or else a solemn warning. The consequence is that we have to piece together unconsidered incidents and the accidental record of features in order to obtain an approximate estimate. We may believe, for instance, that a faithful and unprejudiced study of the emperor Julian, from the life, would be a very different thing from the impression left upon us by the passions of Cyril or of Theodoret. In considering what biography, in its pure sense, ought to be, we must insist on what it is not. It is not a philosophical treatise nor a polemical pamphlet. It is not, even, a portion of the human contemporary chronicle. Broad views are entirely out of place in biography, and there is perhaps no greater literary mistake than to attempt what is called the "Life and Times" of a man. In an adequate record of the "times," the man is bound to sink into significance; even a "Life and Times" of Napoleon I. would be an impossible task. History deals with fragments of the vast roll of events; it must always begin abruptly and close in the middle of affairs; it must always deal, impartially, with a vast number of persons. Biography is a study sharply defined by two definite events, birth and death. It fills its canvas with one figure, and other personages, however great in themselves, must always be subsidiary to the central hero. The only remnant of the old rhetorical purpose of "lives" which clearer modern purpose can afford to retain is the relative light thrown on military or intellectual or social genius by the achievements of the selected subject. Even this must be watched with great care, lest the desire to illuminate that genius, and make it consistent, should lead the biographer to glose over frailties or obscure irregularities. In the old "lives" of great men, this is precisely what was done. If the facts did not lend themselves to the great initial thesis, so much the worse for them. They must be ignored or falsified, since the whole object of the work was to "teach a lesson," to magnify a certain tendency of conduct. It was very difficult to persuade the literary world that, whatever biography is, it is not an opportunity for panegyric or invective, and the lack of this perception destroys our faith in most of the records of personal life in ancient and medieval times. It is impossible to avoid suspecting that Suetonius loaded his canvas with black in order to excite hatred against the Roman emperors; it is still more difficult to accept more than one page in three of the stories of the professional hagiographers. As long as it was a pious merit to deform the truth, biography could not hope to flourish. It appears to have originally asserted itself when the primitive instinct of sympathy began to have free play, that is to say, not much or often before the 17th century. Moreover, the peculiar curiosity which legitimate biography satisfies is essentially a modern thing; and presupposes our observation of life not unduly clouded by moral passion or prejudice.

Among the ancients, biography was not specifically cultivated until comparatively later times. The lost "Lives" of Critias were probably political pamphlets. We meet first with deliberate biography in Xenophon's memoirs of Socrates, a work of epoch-making value. Towards the close of the 1st century, Plutarch wrote one of the most fascinating books in the world's literature, his _Parallel Lives_ of 46 Greeks and Romans. In later Greek, the _Life of Apollonius of Tyana_ was written by Philostratus, who also produced a _Lives of the Sophists_. In the 3rd century, Diogenes Laertius compiled a _Lives of the Philosophers_, which is of greater interest than a _Lives of the Sophists_ composed a hundred years later by Eunapius. Finally in the 10th century, Suidas added a biographical section to his celebrated _Lexicon_. In Latin literature, the earliest biography we meet with is the fragment of the _Illustrious Men_ of Cornelius Nepos. Memoirs began to be largely written at the close of the Augustan age, but these, like the _Life of Alexander the Great_, by Q. Curtius Rufus, were rather historical than biographical. Tacitus composed a life of his father-in-law, Agricola; this is a work of the most elegant and stately beauty. Suetonius was the author of several biographical compilations, of which the _Lives of the Twelve Caesars_ is the best-known; this was produced in the year 120. Marius Maximus, in the 4th century, continued the series of emperors down to Heliogabalus, but his work has not been preserved. The _Augustan History_, finished under Constantine, takes its place, and was concluded and edited by Flavius Vopiscus.

Biography hardly begins to exist in English literature until the close of the reign of Henry VIII. William Roper (1496-1578) wrote a touching life of his father-in-law, Sir Thomas More, and George Cavendish (1500-1561?), a memoir of Cardinal Wolsey which is a masterpiece of liveliness and grace. It is with these two works, both of which remained in manuscript until the 17th century, that biography in England begins. The lives of English writers compiled by John Bale (1495-1563) are much more primitive and slight. John Leland (d. 1552) and John Pits (1560-1616) were antiquaries who affected a species of biography. In the early part of the 17th century, the absence of the habit of memoir writing extremely impoverishes our knowledge of the illustrious authors of the age, of none of whom there are preserved such records as our curiosity would delight in. The absence of any such chronicle was felt, and two writers, Thomas Heywood and Sir Aston Cokayne, proposed to write lives of the poets of their time. Unfortunately they never carried their plans into execution. The pioneer of deliberate English biography was Izaak Walton, who, in 1640, published a _Life of Donne_, followed in 1651 by that of _Sir Henry Wotton_, in 1665 by that of _Richard Hooker_, in 1670 by that of _George Herbert_, and in 1678 by that of _Dr Robert Saunderson_. These five reprinted, under the title of _Walton's Lives_, were not only charming in themselves, but the forerunners of a whole class of English literature. Meanwhile, Fuller was preparing his _History of the Worthies of England_, which appeared after his death, in 1662, and John Aubrey (1626-1697) was compiling his _Minutes of Lives_, which show such a perfect comprehension of the personal element that should underlie biography; these have only in our own days been completely given to the public. Edward, Lord Herbert of Cherbury (1583-1648), wrote a brilliant autobiography, first printed in 1764; that of Anne Harrison, Lady Fanshawe (1625-1680), remained unknown until 1829. A very curious essay in biography is the memoir of Colonel John Hutchinson, written by his widow, Lucy, between 1664 and 1671. Margaret Lucas, duchess of Newcastle (1624?-1674), wrote her own life (1656) and that of her duke (1667). The _Athenae Oxonienses_ of Anthony a Wood (1632-1695) was a complicated celebration of the wit, wisdom and learning of Oxford notabilities since the Reformation. In 1668 Thomas Sprat (1635-1713) wrote a _Life of Cowley_, which was very much admired and which exercised for many years a baneful influence on British biography. Sprat considered that all familiar anecdote and picturesque detail should be omitted in the composition of a memoir, and that moral effect and a solemn vagueness should be aimed at. The celebrated funeral orations of Jeremy Taylor were of the same order of eloquence, and the wind of those grandiose compositions destroyed the young shoot of genuine and simple biography which had budded in Walton and Aubrey.

From this time forth, for more than half a century, English biography became a highly artificial and rhetorical thing, lacking all the salient features of honest portraiture. William Oldys (1696-1761) was the first to speak out boldly; in 1747, in the preface to the _Biographia Britannica_, he pointed out "the cruelty, we might even say the impiety, of sacrificing the glory of great characters to trivial circumstances and mere conveniency," and attacked the timid and scrupulous superficiality of those who undertook to write lives of eminent men, while omitting everything which gave definition to the portrait. In 1753 the _Lives of the Poets_, which bore the name of Theophilus Cibber (1703-1758), but was mainly written by Robert Shiels (d. 1753), gave a great deal of valuable information with regard to the personal adventures of our writers. Dr Johnson's _Life of Savage_ (1744), though containing some passages of extreme interest, was a work of imperfect form, but Mason's _Life and Letters of Gray_ (1774) marks a great advance in the art of biography. This was the earliest memoir in which correspondence of a familiar kind was used to illustrate and to expand the narrative, and Mason's _Gray_ is really the pioneer of almost all modern English biography. For the first time it was now admitted that letters to intimate friends, not written with a view to publication, might be used with advantage to illustrate the real character of the writer. Boswell, it is certain, availed himself of Mason's example, while improving upon it, and in 1791 he published his _Life of Dr Samuel Johnson_, which is the most interesting example of biography existing in English, or perhaps in any language.

As soon as the model of Boswell became familiar to biographers, it could no longer be said that any secret in the art was left unknown to them, and the biographies of the 19th century are all more or less founded upon the magnificent type of the _Life of Johnson_. But few have even approached it in courage, picturesqueness or mastery of portraiture. In the next generation Southey's lives of _Nelson_ (1813) and _John Wesley_ (1820) at once became classics; but the pre-eminent specimen of early 19-century biography is Lockhart's superb _Life of Sir Walter Scott_ (1837-1838). The biographies of the 19th century are far too numerous to be mentioned here in detail; in the various articles dedicated to particular men and women in this Encyclopaedia, the date and authorship of the authoritative life of each person will in most cases be found appended. Towards the close of the century there was unquestionably an excess, and even an abuse, in the habit of biography. It became the custom a few years or even months after the decease of an individual who had occupied a passing place in the eyes of the public, to issue a "Life" of him; in many cases such biography was a labour of utter supererogation. But the custom has become general, and it is very unlikely, notwithstanding the ephemeral interest of readers in the majority of the subjects, that it will ever go out of fashion, for it directly indulges both vanity and sentiment. What is true of Great Britain is true, though in less measure, of all other modern nations, and it is not necessary here to deal with more than the early manifestations of biography in the principal European literatures.

To Switzerland appears due the honour of having given birth to the earliest biographical dictionary ever compiled, the _Bibliotheca Universalis_ of Konrad Gesner (1516-1565), published at Zuerich in Latin, Greek and Hebrew, from 1545 to 1549. A very rare work, by a writer of the greatest obscurity, the _Prosopographia_ of Verdier de Vauprivas, published at Lyons in 1573, professed to deal with the lives of all illustrious persons who had flourished since the beginning of the world.

In medieval and renaissance France there existed numerous memoirs and histories, such as those of Brantome, into which the lives of great men were inserted, and in which a biographical character was given to studies of virtue and valour, or of the reverse. But the honour of being the earliest deliberate contribution to biography is generally given to the _Acta Sanctorum_, compiled by the Bollandists, the first volume of which appeared in 1653. This was the first biographical dictionary compiled in Europe, and its publication produced a great sensation. It was confined to the lives of saints and martyrs, but in 1674 Louis Moreri, in his _Grand Dictionnaire_, included a biographical section of a general character. But the earliest biographical dictionary which had anything of a modern form was the celebrated _Dictionnaire historique et critique_ of Pierre Bayle, in 1696; the lives in this great work, however, are too often used as mere excuses for developing the philosophical and controversial views of the author; they are nevertheless the result of genuine research and have a true biographical view. The _Dictionnaire_ was translated into English in 1734, and had a wide influence in creating a legitimate interest in biography in England.

In Italian literature, biography does not take a prominent place until the 15th century. _The Lives of Illustrious Florentines_, in which a valuable memoir of Dante occurs, was written in Latin by Filippo Villani. Vespasiano da Bistrici (1421-1498) compiled a set of biographies of his contemporaries, which are excellent of their kind. The so-called _Life of Castruccio Castracani_, by Machiavelli, is hardly a biography, but a brilliant essay on the ideals of statecraft. Paolo Giovio (1483-1552) wrote the lives of poets and soldiers whom he had known. All these attempts, however, seem insignificant by the side of the autobiography of Benvenuto Cellini (1501-1571), confessedly one of the most entertaining works of the world's literature. A great deal of biography is scattered throughout the historical compilations of the Italian renaissance, and the _Lives of the Artists_, by Giorgio Vasari (1512-1574), is a storehouse of anecdotes admirably told. We find nothing else that requires special mention till we reach the memoir-writers of the 18th century, with the autobiographies of Count Carlo Gozzi and Alfieri; and on the whole, Italy, although adopting in the 19th century the habit of biography, has rarely excelled in it.

In Spanish literature Fernan Perez de Guzman (1378-1460), with great originality, enshrined, in his _Generations and Likenesses_, a series of admirable literary portraits; he has been called the Plutarch of Spain. But, in spite of numerous lives of saints, poets and soldiers, Spanish literature has not excelled in biography, nor has it produced a single work of this class which is universally read. In Germany there is little to record before the close of the 18th century.

In the course of the 19th century a new thing in biography was invented, in the shape of dictionaries of national biography. Of these, the first which was carried to a successful conclusion was the Swedish (1835-1857), which occupied 23 volumes. This dictionary was followed by the Dutch (1852-1878), in 24 volumes; the Austrian (1856-1891), in 35 volumes; the Belgian (which was begun in 1866); the German (1875-1900), in 45 volumes; and others, representing nearly all the countries of Europe. England was behind the competitors named above, but when she joined the ranks a work was produced the value of which can hardly be exaggerated. The project was started in 1882 by the publisher George Smith (1824-1901), who consulted Mr (afterwards Sir) Leslie Stephen. The first volume of the English _Dictionary of National Biography_ was published on the 1st of January 1885, under Stephen's editorship. A volume was published quarterly, with complete punctuality until Midsummer 1900, when volume 63 closed the work, which was presently extended by the issue of three supplementary volumes. In May 1891 Leslie Stephen resigned the editorship and was succeeded by Mr Sidney Lee, who conducted the work to its prosperous close, bringing it up to the death of Queen Victoria. The _Dictionary of National Biography_ contains the lives of more than 30,000 persons, and has proved of inestimable service in elucidating the private annals of the British people. (E. G.)

BIOLOGY (Gr. [Greek: bios], life). The biological sciences are those which deal with the phenomena manifested by living matter; and though it is customary and convenient to group apart such of these phenomena as are termed mental, and such of them as are exhibited by men in society, under the heads of psychology and sociology, yet it must be allowed that no natural boundary separates the subject matter of the latter sciences from that of biology. Psychology is inseparably linked with physiology; and the phases of social life exhibited by animals other than man, which sometimes curiously foreshadow human policy, fall strictly within the province of the biologist.

On the other hand, the biological sciences are sharply marked off from the abiological, or those which treat of the phenomena manifested by not-living matter, in so far as the properties of living matter distinguish it absolutely from all other kinds of things, and as the present state of knowledge furnishes us with no link between the living and the not-living.

These distinctive properties of living matter are--

The properties of living matter.

1. Its _chemical composition_--containing, as it invariably does, one or more forms of a complex compound of carbon, hydrogen, oxygen and nitrogen, the so-called protein or albumin (which has never yet been obtained except as a product of living bodies), united with a large proportion of water, and forming the chief constituent of a substance which, in its primary unmodified state, is known as _protoplasm_.

2. Its _universal disintegration and waste by oxidation; and its concomitant reintegration by the intussusception of new matter_.

A process of waste resulting from the decomposition of the molecules of the protoplasm, in virtue of which they break up into more highly oxidated products, which cease to form any part of the living body, is a constant concomitant of life. There is reason to believe that carbonic acid is always one of these waste products, while the others contain the remainder of the carbon, the nitrogen, the hydrogen and the other elements which may enter into the composition of the protoplasm.

The new matter taken in to make good this constant loss is either a ready-formed protoplasmic material, supplied by some other living being, or it consists of the elements of protoplasm, united together in simpler combinations, which consequently have to be built up into protoplasm by the agency of the living matter itself. In either case, the addition of molecules to those which already existed takes place, not at the surface of the living mass, but by interposition between the existing molecules of the latter. If the processes of disintegration and of reconstruction which characterize life balance one another, the size of the mass of living matter remains stationary, while, if the reconstructive process is the more rapid, the living body _grows_. But the increase of size which constitutes growth is the result of a process of molecular intussusception, and therefore differs altogether from the process of growth by accretion, which may be observed in crystals and is effected purely by the external addition of new matter--so that, in the well-known aphorism of Linnaeus, the word "grow" as applied to stones signifies a totally different process from what is called "growth" in plants and animals.

3. Its _tendency to undergo cyclical changes_.

In the ordinary course of nature, all living matter proceeds from pre-existing living matter, a portion of the latter being detached and acquiring an independent existence. The new form takes on the characters of that from which it arose; exhibits the same power of propagating itself by means of an offshoot; and, sooner or later, like its predecessor, ceases to live, and is resolved into more highly oxidated compounds of its elements.

Thus an individual living body is not only constantly changing its substance, but its size and form are undergoing continual modifications, the end of which is the death and decay of that individual; the continuation of the kind being secured by the detachment of portions which tend to run through the same cycle of forms as the parent. No forms of matter which are either not living, or have not been derived from living matter, exhibit these three properties, nor any approach to the remarkable phenomena defined under the second and third heads. But in addition to these distinctive characters, living matter has some other peculiarities, the chief of which are the dependence of all its activities upon moisture and upon heat, within a limited range of temperature, and the fact that it usually possesses a certain structure or organization.

Life conditioned by moisture.

As has been said, a large proportion of water enters into the composition of all living matter; a certain amount of drying arrests vital activity, and the complete abstraction of this water is absolutely incompatible with either actual or potential life. But many of the simpler forms of life may undergo desiccation to such an extent as to arrest their vital manifestations and convert them into the semblance of not-living matter, and yet remain potentially alive. That is to say, on being duly moistened they return to life again. And this revivification may take place after months, or even years, of arrested life.

Life conditioned by temperature.

The properties of living matter are intimately related to temperature. Not only does exposure to heat sufficient to coagulate protein matter destroy life, by demolishing the molecular structure upon which life depends; but all vital activity, all phenomena of nutritive growth, movement and reproduction are possible only between certain limits of temperature. These limits may be set down as from a little above the freezing point of water to a little below the boiling point It is to be noted, however, that these limits apply to the living matter itself, and many of the apparent exceptions are due to cases in which the living matter is enclosed in protective wrappings capable of resisting heat and cold. In many low organisms, such as the spores of bacteria, the thick, non-conducting wall may preserve the living protoplasm from subjection to external temperatures below freezing point, or above boiling point, but all the evidence goes to show that applications of such cold or heat, if prolonged or arranged so as to penetrate to the living matter, destroy life. In warm-blooded animals, such as birds and mammals, protective mechanisms for the regulation of temperature enable them to endure exposure to extreme heat or cold, but in such cases the actually living cells do not appreciably rise or fall in temperature. A variation of a very few degrees in the blood itself produces death.

Recent investigations point to the conclusion that the immediate cause of the arrest of vitality, in the first place, and of its destruction, in the second, is the coagulation of certain substances in the protoplasm, and that the latter contains various coagulable matters, which solidify at different temperatures. And it remains to be seen, how far the death of any form of living matter, at a given temperature, depends on the destruction of its fundamental substance at that heat, and how far death is brought about by the coagulation of merely accessory compounds.

Life and organization.

It may be safely said of all those living things which are large enough to enable us to trust the evidence of microscopes, that they are heterogeneous optically, and that their different parts, and especially the surface layer, as contrasted with the interior, differ physically and chemically; while, in most living things, mere heterogeneity is exchanged for a definite structure, whereby the body is distinguished into visibly different parts, which possess different powers or functions. Living things which present this visible structure are said to be _organized_; and so widely does organization obtain among living beings, that _organized_ and _living_ are not unfrequently used as if they were terms of co-extensive applicability. This, however, is not exactly accurate, if it be thereby implied that all living things have a visible organization, as there are numerous forms of living matter of which it cannot properly be said that they possess either a definite structure or permanently specialized organs: though, doubtless, the simplest particle of living matter must possess a highly complex molecular structure, which is far beyond the reach of vision.

The broad distinctions which, as a matter of fact, exist between every known form of living substance and every other component of the material world, justify the separation of the biological sciences from all others. But it must not be supposed that the differences between living and not-living matter are such as to justify the assumption that the forces at work in the one are different from those which are to be met with in the other. Considered apart from the phenomena of consciousness, the phenomena of life are all dependent upon the working of the same physical and chemical forces as those which are active in the rest of the world. It may be convenient to use the terms "vitality" and "vital force" to denote the causes of certain great groups of natural operations, as we employ the names of "electricity" and "electrical force" to denote others; but it ceases to be proper to do so, if such a name implies the absurd assumption that "electricity" and "vitality" are entities playing the part of efficient causes of electrical or vital phenomena. A mass of living protoplasm is simply a molecular machine of great complexity, the total results of the working of which, or its vital phenomena, depend--on the one hand, upon its construction, and, on the other, upon the energy supplied to it; and to speak of "vitality" as anything but the name of a series of operations is as if one should talk of the "horologity" of a clock.

Classification of the phenomena of life.

Living matter, or protoplasm and the products of its metamorphosis, may be regarded under four aspects:--

1. It has a certain external and internal form, the latter being more usually called structure;

2. It occupies a certain position in space and in time;

3. It is the subject of the operation of certain forces in virtue of which it undergoes internal changes, modifies external objects, and is modified by them; and

4. Its form, place and powers are the effects of certain causes.

In correspondence with these four aspects of its subject, biology is logically divisible into four chief subdivisions--I. MORPHOLOGY; II. DISTRIBUTION; III. PHYSIOLOGY; IV. AETIOLOGY.

Various accidental circumstances, however, have brought it about that the actual distribution of scientific work does not correspond with the logical subdivisions of biology. The difference in technical methods and the historical evolution of teaching posts (for in all civilized countries the progress of biological knowledge has been very closely associated with the existence of institutions for the diffusion of knowledge and for professional education) have been the chief contributory causes to this practical confusion. Details of the morphology of plants will be found in the articles relating to the chief groups of plants, those of animals in the corresponding articles on groups of animals, while the classification of animals adopted in this work will be found in the article ZOOLOGY. Distribution is treated of under ZOOLOGICAL DISTRIBUTION, PLANKTON, PALAEONTOLOGY and PLANTS: _Distribution_. PHYSIOLOGY and its allied articles deal with the subject generally and in relation to man, while the special physiology of plants is dealt with in a section of the article PLANTS. Aetiology is treated of under the heading EVOLUTION. But practical necessity has given rise to the existence of many other divisions; see CYTOLOGY, for the structure of cells; EMBRYOLOGY, for the development of individual organisms; HEREDITY and REPRODUCTION, for the relations between parents and offspring. (T. H. H.; P. C. M.)

BION, Greek bucolic poet, was born at Phlossa near Smyrna, and flourished about 100 B.C. The account formerly given of him, that he was the contemporary and imitator of Theocritus, the friend and tutor of Moschus, and lived about 280 B.C., is now generally regarded as incorrect. W. Stein (_De Moschi et Bionis aetate_, Tuebingen, 1893) puts Bion, chiefly on metrical grounds, in the first half of the 1st century B.C. Nothing is known of him except that he lived in Sicily. The story that he died of poison, administered to him by some jealous rivals, who afterwards suffered the penalty of their crime, is probably only an invention of the author of the [Greek: Epitaphios Bionos] (see MOSCHUS). Although his poems are included in the general class of bucolic poetry, the remains show little of the vigour and truthfulness to nature characteristic of Theocritus. They breathe an exaggerated sentimentality, and show traces of the overstrained reflection frequently observable in later developments of pastoral poetry. The longest and best of them is the _Lament for Adonis_ ([Greek: Epitaphios Adonidos]). It refers to the first day of the festival of Adonis (q.v.), on which the death of the favourite of Aphrodite was lamented, thus forming an introduction to the _Adoniazusae_ of Theocritus, the subject of which is the second day, when the reunion of Adonis and Aphrodite was celebrated. Fragments of his other pieces are preserved in Stobaeus; the epithalamium of Achilles and Deidameia is not his.

Bion and Moschus have been edited separately by G. Hermann (1849) and C. Ziegler (Tuebingen, 1869), the _Epitaphios Adonidos_ by H.L. Ahrens (1854) and E. Hiller in _Beitraege zur Textegeschichte der griechischen Bukoliker_ (1888). Bion's poems are generally included in the editions of Theocritus. There are English translations by J. Banks (1853) in Bohn's _Classical Library_, and by Andrew Long (1889), with Theocritus and Moschus; there is an edition of the text by U. Wilamowitz-Moellendorff in the Oxford _Scriptorum Classicorum Bibliotheca_ (1905). On the date of Bion see F. Buecheler in _Rheinisches Museum_, xxx. (1875), pp. 33-41; also G. Knaack in Pauly-Wissowa's _Realencyclopaedie_, s.v.; and F. Susemihl, _Geschichte der griechischen Litteratur in der Alexandrinerzeit_, i. (1891), p. 233.

BION, of Borysthenes (Olbia), in Sarmatia, Greek moralist and philosopher, flourished in the first half of the 3rd century B.C. He was of low origin, his mother being a courtesan and his father a dealer in salt fish, with which he combined the occupation of smuggling. Bion, when a young man, was sold as a slave to a rhetorician, who gave him his freedom and made him his heir. After the death of his patron, Bion went to Athens to study philosophy. Here he attached himself in succession to the Academy, the Cynics, the Cyrenaics and the Peripatetics. One of his teachers was the Cyrenaic Theodorus, called "the atheist," whose influence is clearly shown in Bion's attitude towards the gods. After the manner of the sophists of the period, Bion travelled through Greece and Macedonia, and was admitted to the literary circle at the court of Antigonus Gonatas. He subsequently taught philosophy at Rhodes and died at Chalcis in Euboea. His life was written by Diogenes Laertius. Bion was essentially a popular writer, and in his _Diatribae_ he satirized the follies of mankind in a manner calculated to appeal to the sympathies of a low-class audience. While eulogizing poverty and philosophy, he attacked the gods, musicians, geometricians, astrologers, and the wealthy, and denied the efficacy of prayer. His influence is distinctly traceable in succeeding writers, e.g. in the satires of Menippus. Horace (_Epistles_, ii. 2. 60) alludes to his satires and caustic wit (_sal nigrum_). An idea of his writings can be gathered from the fragments of Teles, a cynic philosopher who lived towards the end of the 3rd century, and who made great use of them. Specimens of his apophthegms may be found in Diogenes Laertius and the florilegium of Stobaeus, while there are traces of his influence in Seneca.

See Hoogvliet, _De Vita, Doctrina, et Scriptis Bionis_ (1821); Rossignol, _Fragmenta Bionis Borysthenitae_ (1830); Heinze, _De Horatio Bionis Imitatore_ (1889).

BIOT, JEAN BAPTISTE (1774-1862), French physicist, was born at Paris on the 21st of April 1774. After serving for a short time in the artillery, he was appointed in 1797 professor of mathematics at Beauvais, and in 1800 he became professor of physics at the College de France, through the influence of Laplace, from whom he had sought and obtained the favour of reading the proof sheets of the _Mecanique celeste_. Three years later, at an unusually early age, he was elected a member of the Academy of Sciences, and in 1804 he accompanied Gay Lussac on the first balloon ascent undertaken for scientific purposes. In 1806 he was associated with F.J.D. Arago, with whom he had already carried out investigations on the refractive properties of different gases, in the measurement of an arc of the meridian in Spain, and in subsequent years he was engaged in various other geodetic determinations. In 1814 he was made chevalier and in 1849 commander, of the Legion of Honour. He failed in his ambition of becoming perpetual secretary of the Academy of Sciences, but was somewhat consoled by his election as a member of the French Academy in 1856. He died in Paris on the 3rd of February 1862. His researches extended to almost every branch of physical science, but his most important work was of an optical character. He was especially interested in questions relating to the polarization of light, and his observations in this field, which gained him the Rumford medal of the Royal Society in 1840, laid the foundations of the polarimetric analysis of sugar.

Biot was an extremely prolific writer, and besides a great number of scientific memoirs, biographies, &c., his published works include: _Analyse de la mecanique celeste de M. Laplace_ (1801); _Traite analytique des courbes et des surfaces du second degre_ (1802); _Recherches sur l'integration des equations differentielles partielles et sur les vibrations des surfaces_ (1803); _Traite de physique_ (1816); _Recueil d'observations geodesiques, astronomiques et physiques executees en Espagne et Ecosse_, with Arago (1821); _Memoire sur la vraie constitution de l'atmosphere terrestre_ (1841); _Traite elementaire d'astronomie physique_ (1805); _Recherches sur_ _plusieurs points de l'astronomie egyptienne_ (1823); _Recherches sur l'ancienne astronomie chinoise_ (1840); _Etudes sur l'astronomie indienne et sur l'astronomie chinoise_ (1862); _Essai sur l'histoire generale des sciences pendant la Revolution_ (1803); _Discours sur Montaigne_ (1812); _Lettres sur l'approvisionnement de Paris et sur le commerce des grains_ (1835); _Melanges scientifiques et litteraires_ (1858).

His son, EDOUARD CONSTANT BIOT (1803-1850), after amassing a competence from railway engineering, turned to the study of Chinese subjects, and published _Causes de l'abolition de l'esclavage ancien en occident_ (1840); _Dictionnaire des noms anciens et modernes des villes et des arrondissements compris dans l'empire chinois_ (1842); _Essai sur l'histoire de l'instruction publique en Chine et de la corporation des lettres_ (1847); _Memoire sur les colonies militaires et agricoles des chinois_ (1850).

BIOTITE, an important rock-forming mineral belonging to the group of micas (q.v.). The name was given by J.F.L. Hausmann in 1847 in honour of the French physicist, J.B. Biot, who in 1816 found the magnesia-micas to be optically uniaxial or nearly so. The magnesia-micas are now referred to the species biotite and phlogopite, which differ in that the former contains a considerable but widely varying amount of iron. Biotite is an orthosilicate of aluminium, magnesium, ferrous and ferric iron, potassium and basic hydrogen, with small amounts of calcium, sodium, lithium, fluorine, titanium, &c., and ranges in composition between (H, K)2(Mg, Fe)4(Al, Fe)2(SiO4)4 and (H, K)2(Mg, Fe)2Al2(SiO4)3.

Like the other micas, it is monoclinic with pseudo-hexagonal symmetry (figs. 1, 2) and possesses a perfect cleavage in one direction (c). Biotite is, however, readily distinguished by its darker colour, strong pleochroism, and small optic axial angle. The colour is usually dark-green or brown; thick crystals are often deep-black and opaque. The absorption of light-rays vibrating parallel to the cleavage is much greater than of rays vibrating in a direction perpendicular thereto, and in dark-coloured crystals the former are almost completely absorbed. The angle between the optic axes is usually very small, the crystals being often practically uniaxial; an axial angle of 50 deg. has, however, been recorded in a dark-coloured biotite. The specific gravity of biotite is, as a rule, higher than that of other micas, varying from 2.7 to 3.1 according to the amount of iron present. The hardness is 21/2 to 3.

Several varieties of biotite are distinguished. By G. Tschermak it is divided into two classes, _meroxene_ and _anomite_; in the former the plane of the optic axis coincides with the plane of symmetry, whilst in the latter it is perpendicular thereto. Meroxene includes nearly all ordinary biotite, and is the name given by A. Breithaupt in 1841 to the Vesuvian crystals; on the other hand, anomite (named from [Greek: anomos], "contrary to law") is of rare occurrence. Haughtonite and siderophyllite are black varieties rich in ferrous iron, and lepidomelane (from [Greek: lepis], a scale, and [Greek: melas], black) is a variety rich in ferric iron. In barytobiotite and manganophyllite the magnesia is partly replaced by baryta and manganous oxide respectively. Rubellane, hydrobiotite, pseudobiotite, and others are altered forms of biotite, which is a mineral particularly liable to decomposition with the production of chlorites and vermiculites.

Biotite is a common constituent of igneous and crystalline rocks; in granite, gneiss and mica-schist it is often associated with muscovite (white mica), the two kinds having sometimes grown in parallel position. In volcanic rocks, and in nearly all other kinds of igneous rocks with the exception of granite, biotite occurs to the exclusion of the muscovite. In the dyke-rocks known as mica-traps or mica-lamprophyres biotite is especially abundant. It is also one of the most characteristic products of contact-metamorphism, being developed in sedimentary and other rocks at their contact with granite masses. In the ejected blocks of crystalline limestone of Monte Somma, Vesuvius, the most perfectly developed crystals of biotite (figs. 1, 2), or indeed of any of the micas, are found in abundance, associated with brilliant crystals of augite, olivine, humite, &c.

Although biotite (black mica) is much more common and widely distributed than white mica, yet it is of far less economic importance. The small size of the sheets, their dark colour and want of transparency render the material of little value. Large, cleavable masses yielding fine smoky-black and green sheets, sufficiently elastic for industrial purposes, are, however, found in Renfrew county, Ontario. (L. J. S.)

BIPARTITE (from the Lat. _bi-_, two, and _partire_, to divide). In a general sense, the word means having two corresponding parts or in duplicate. In geometry, a bipartite curve consists of two distinct branches (see PARABOLA, figs. 3, 5). In botany, the word is applied to leaves divided into two parts near the base. A _bipartient factor_ is a number whose square exactly divides another number. In zoology, the _Bipartiti_ was a name given by P.A. Latreille to a group of carnivorous _Coleoptera_.

BIPONT EDITIONS, the name of a famous series of editions, in 50 volumes, of Greek and Latin classical authors, so called from Bipontium, the modern Latin name of Zweibruecken or Deux-Ponts in Bavaria, where they were first issued in 1779. Their place of publication was afterwards transferred to Strassburg.

See Butters, _Uber die Editiones Bipontinae_ (1877).

BIQUADRATIC (from the Lat. _bi-, bis_, twice, and _quadratus_, squared). In mathematics, the biquadratic power or root of a quantity is its fourth power or root (see ALGEBRA); a biquadratic equation is an equation in which the highest power of the unknown is the fourth (see EQUATION: _Biquadratic_).

BIQUINTILE (from Lat. prefix _bi-_, twice, _quintilis_, fifth), the aspect of two planets which are distant from each other twice the fifth part of a great circle, i.e. 144 deg.. It was one of the new aspects introduced by Kepler.

BIRBHUM, a district of British India in the Burdwan division of Bengal, situated in the Gangetic plain and partly on the hills, being bounded on the south by the river Ajai. The administrative headquarters are at Suri, which is the only town in the district. The area comprises 1752 sq. m. The eastern portion of the district is the ordinary alluvial plain of the Gangetic delta; the western part consists of undulating beds of laterite resting on a rock basis, and covered with small scrub jungle. The Ajai, Bakheswar and Mor or Maurakshi, are the principal rivers of the district, but they are merely hill streams and only navigable in the rains. In 1901 the population was 902,280, showing an increase of 13% in the decade. The principal industry is the spinning and weaving of silk, chiefly from tussur or jungle silkworms. There are also several lac factories. The loop-line of the East Indian railway runs through the district, with a junction at Nalhati for Murshidabad.

_History._--Birbhum in the early part of the 13th century was a Hindu state, with its capital at Rajnagar or Nagar. In the course of the century it was conquered by the Pathans and formed part of the Pathan kingdom of Bengal. At the beginning of the 18th century it appears as a kind of military fief held under the nawab of Murshidabad by one Asadullah Pathan, whose family had probably been its chieftains since the fall of the Pathan dynasty of Bengal in 1600. It passed into British possession in 1765, but the East India Company did not assume its direct government until 1787, when that course became necessary. In the interval it had been a prey to armed bands from the highlands of Chota Nagpur, with whom the raja was unable to cope, and who practically brought the trade of the Company in the district to a standstill. The two border principalities of Birbhum and Bankura were accordingly united into a district under a British collector, being, however, separated again in 1793. By 1789, after considerable trouble, the marauders were driven back into their mountains, and since that time (except during the Santal rising of 1855) the district has been one of the most peaceful and prosperous in India.

See _Imperial Gazetteer of India_ (Oxford, 1908), vol. viii. _s.v_.

BIRCH, SAMUEL (1813-1885), English Egyptologist and antiquary, was born on the 3rd of November 1813, being the son of the rector of St Mary Woolnoth, London. From an early age he manifested a tendency to the study of out-of-the-way subjects, and after a brief employment in the Record Office obtained in 1836 an appointment in the antiquities department of the British Museum on account of his knowledge of Chinese. He soon extended his researches to Egyptian, and when the cumbrous department came to be divided he was appointed to the charge of the Egyptian and Assyrian branch. In the latter language he had assistance, but for many years there was only one other person in the institution--in a different department--who knew anything of ancient Egyptian, and the entire arrangement of the department devolved upon Birch. He found time nevertheless for Egyptological work of the highest value, including a hieroglyphical grammar and dictionary, translations of _The Book of the Dead_ and the Harris papyrus, and numerous catalogues and guides. He further wrote what was long a standard history of pottery, investigated the Cypriote syllabary, and proved by various publications that he had not lost his old interest in Chinese. Paradoxical in many of his views on things in general, he was sound and cautious as a philologist; while learned and laborious, he possessed much of the instinctive divination of genius. He died on the 27th of December 1885.

BIRCH, THOMAS (1705-1766), English historian, son of Joseph Birch, a coffee-mill maker, was born at Clerkenwell on the 23rd of November 1705. He preferred study to business, but as his parents were Quakers he did not go to the university. Notwithstanding this circumstance, he was ordained deacon in the Church of England in 1730 and priest in 1731. As a strong supporter of the Whigs, he gained the favour of Philip Yorke, afterwards lord chancellor and first earl of Hardwicke, and his subsequent preferments were largely due to this friendship. He held successively a number of benefices in different counties, and finally in London. In 1735 he became a member of the Society of Antiquaries, and was elected a fellow of the Royal Society, of which he was secretary from 1752 to 1765. In 1728 he had married Hannah Cox, who died in the following year. Birch was killed on the 9th of January 1766 by a fall from his horse, and was buried in the church of St Margaret Pattens, London, of which he was then rector. He left his books and manuscripts to the British Museum, and a sum of about L500 to increase the salaries of the three assistant librarians.

Birch had an enormous capacity for work and was engaged in a large number of literary undertakings. In spite of their dulness many of his works are of considerable value, although Horace Walpole questioned his "parts, taste and judgment." He carried on an extensive correspondence with some of the leading men of his time, and many of his letters appear in _Literary Anecdotes of the 18th Century_ (London, 1812-1815) and _Illustrations of the Literary History of the 18th Century_ (London, 1817-1858) by J. Nichols, in the _Bibliotheca Topographica Britannica_, vol. iii. (London, 1780-1790), and in Boswell's _Life of Johnson_. Birch wrote most of the English lives in the _General Dictionary, Historical and Critical_, 10 vols. (London, 1734-1741), assisted in the composition of the _Athenian Letters_ (London, 1810), edited the _State Papers_ of John Thurloe (London, 1742) and the _State Papers_ of W. Murdin (London, 1759). He also wrote a _Life of the Right Honourable Robert Boyle_ (London, 1744); _Inquiry into the share which King Charles I. had in the transactions of the Earl of Glamorgan for bringing over a body of Irish rebels_ (London, 1756); _Historical view of Negotiations between the Courts of England, France and Brussels 1592-1617_ (London, 1749); _Life of Archbishop Tillotson_ (London, 1753); _Memoirs of the Reign of Queen Elizabeth from 1581_ (London, 1754); _History of the Royal Society of London_ (London, 1756-1757); _Life of Henry, Prince of Wales_ (London, 1760), and many other works. Among the papers left at his death were some which were published in 1848 as the _Court and Times of James I_. and the _Court and Times of Charles I_.

See W.P. Courtney in the _Dictionary of National Biography_, vol. v. (1886); A. Kippis, _Biographia Britannica_ (London, 1778-1793); Horace Walpole, _Letters_ (London, 1891).

BIRCH (_Betula_), a genus of plants allied to the alder (_Alnus_), and like it a member of the natural order _Betulaceae_. The various species of birch are mostly trees of medium size, but several of them are merely shrubs. They are as a rule of a very hardy character, thriving best in northern latitudes--the trees having round, slender branches, and serrate, deciduous leaves, with barren and fertile catkins on the same tree, and winged fruits, the so-called seeds. The bark in most of the trees occurs in fine soft membranous layers, the outer cuticle of which peels off in thin, white, papery sheets.

The common white or silver birch (_B. alba_) (see fig.) grows throughout the greater part of Europe, and also in Asia Minor, Siberia and North America, reaching in the north to the extreme limits of forest vegetation, and stretching southward on the European continent as a forest tree to 45 deg. N. lat., beyond which birches occur only in special situations or as isolated trees. It is well known in England for its graceful habit, the slender, grey--or white--barked stem, the delicate, drooping branches and the quivering leaves, a bright, clear green in spring, becoming duller in the summer, but often keeping their greenness rather late into the autumn. The male and female flowers are borne on separate catkins in April and May. It is a shortlived tree, generally from 40 to 50 ft. high with a trunk seldom more than 1 ft. in diameter. It flourishes in light soils and is one of the few trees that will grow amongst heather; owing to the large number of "winged seeds" which are readily scattered by the wind, it spreads rapidly, springing up where the soil is dry and covering clearings or waste places.

The birch is one of the most wide-spread and generally useful of forest trees of Russia, occurring in that empire in vast forests, in many instances alone, and in other cases mingled with pines, poplars and other forest trees. The wood is highly valued by carriage-builders, upholsterers and turners, on account of its toughness and tenacity, and in Russia it is prized as firewood and a source of charcoal. A very extensive domestic industry in Russia consists in the manufacture of wooden spoons, which are made to the extent of 30,000,000 annually, mostly of birch. Its pliant and flexible branches are made into brooms; and in ancient Rome the fasces of the lictors, with which they cleared the way for the magistrates, were made up of birch rods. A similar use of birch rods has continued among pedagogues to times so recent that the birch is yet, literally or metaphorically, the instrument of school-room discipline. The bark of the common birch is much more durable, and industrially of greater value, than the wood. It is impermeable to water, and is therefore used in northern countries for roofing, for domestic utensils, for boxes and jars to contain both solid and liquid substances, and for a kind of bark shoes, of which it is estimated 25 millions of pairs are annually worn by the Russian peasantry. The jars and boxes of birch bark made by Russian peasants are often stamped with very effective patterns. By dry distillation the bark yields an empyreumatic oil, called _diogott_ in Russia, used in the preparation of Russia leather; to this oil the peculiar pleasant odour of the leather is due. The bark itself is used in tanning; and by the Samoiedes and Kamchatkans it is ground up and eaten on account of the starchy matter it contains. A sugary sap is drawn from the trunk in the spring before the opening of the leaf-buds, and is fermented into a kind of beer and vinegar. The whole tree, but especially the bark and leaves, has a very pleasant resinous odour, and from the young leaves and buds an essential oil is distilled with water. The leaves are used as fodder in northern latitudes.

The species which belong peculiarly to America (_B. lenta, excelsa, nigra, papyracea_, &c.) are generally similar in appearance and properties to _B. alba_, and have the same range of applications. The largest and most valuable is the black birch (_B. lenta_) found abundantly over an extensive area in British North America, growing 60 to 70 ft. high and 2 to 3 ft. in diameter. It is a wood most extensively used for furniture and for carriage-building, being tough in texture and bearing shocks well, while much of it has a handsome grain and it is susceptible of a fine polish. The bark, which is dark brown or reddish, and very durable, is used by Indians and backwoodsmen in the same way as the bark of _B. alba_ is used in northern Europe.

The canoe or paper birch (_B. papyracea_) is found as far north as 70 deg. N. on the American continent, but it becomes rare and stunted in the Arctic circle. Professor Charles Sprague Sargent says: "It is one of the most widely distributed trees of North America. From Labrador it ranges to the southern shores of Hudson's Bay and to those of the Great Bear Lake, and to the valley of the Yukon and the coast of Alaska, forming with the aspen, the larch, the balsam poplar, the banksian pine, the black and white spruces and the balsam fir, the great subarctic transcontinental forest; and southward it ranges through all the forest region of the Dominion of Canada and the northern states." It is a tree of the greatest value to the inhabitants of the Mackenzie river district in British North America. Its bark is used for the construction of canoes, and for drinking-cups, dishes and baskets. From the wood, platters, axe-handles, snow-shoe frames, and dog sledges are made, and it is worked into articles of furniture which are susceptible of a good polish. The sap which flows in the spring is drawn off and boiled down to an agreeable spirit, or fermented with a birch-wine of considerable alcoholic strength. The bark is also used as a substitute for paper. A species (_B. Bhojputtra_) growing on the Himalayan Mountains, as high up as 9000 ft., yields large quantities of fine thin papery bark, extensively sent down to the plains as a substitute for wrapping paper, for covering the "snakes" of hookahs and for umbrellas. It is also said to be used as writing paper by the mountaineers; and in Kashmir it is in general use for roofing houses.

BIRCH-PFEIFFER, CHARLOTTE (1800-1868), German actress and dramatic writer, was born at Stuttgart on the 23rd of June 1800, the daughter of an estate agent named Pfeiffer. She received her early training at the Munich court theatre, and in 1818 began to play leading tragic roles at various theatres. In 1825 she married the historian Christian Birch of Copenhagen, but continued to act. From 1837 to 1843 she managed the theatre at Zuerich. In 1844 she accepted an engagement at the royal theatre in Berlin, to which she remained attached until her death on the 24th of August 1868. Her intimate knowledge of the technical necessities of the stage fitted her for the successful dramatization of many popular novels, and her plays, adapted and original, make twenty-three volumes, _Gesammelte dramatische Werke_ (Leip. 1863-1880). Many still retain the public favour. Her novels and tales, _Gesammelte Novellen und Erzaehlungen_, were collected in three volumes (Leip. 1863-1865).

Her daughter, WILHELMINE VON HILLERN (b. 1836), born at Munich, went on the stage, but retired upon her marriage in 1857. After 1889 she lived in Oberammergau and won a reputation as a novelist. Her most popular works are _Ein Arzt der Seele_ (1869, 4th ed. 1886); and _Die Geier-Wally_ (1883), which was dramatized and translated into English as _The Vulture Maiden_ (Leip. 1876).

BIRD, the common English name for feathered vertebrates, members of the class _Aves_. The word in Old Eng. is _brid_ and in Mid. Eng. _byrd_ or _bryd_, and in early uses meant the young or nestlings only. It is partly due to this early meaning that the derivation from the root of "brood" has been usually accepted; this the _New English Dictionary_ regards as "inadmissible." The word does not occur in any other Teutonic language. As a generic name for the feathered vertebrates "bird" has replaced the older "fowl," a common Teutonic word, appearing in German as _Vogel_. "Bird," when it passed from its earliest meaning of "nestlings," seems to have been applied to the smaller, and "fowl" to the larger species, a distinction which was retained by Johnson. In modern usage "fowl," except in "wild-fowl" or "water-fowl," is confined to domestic poultry.

The scope of the anatomical part of the following article is a general account of the structure of birds (_Aves_) in so far as they, as a class, differ from other vertebrates, notably reptiles and mammals, whilst features especially characteristic, peculiar or unique, have been dwelt upon at greater length so far as space permitted. References to original papers indicate further sources of information. For a comprehensive account the reader may be referred to Prof. M. Fuerbringer's enormous work _Untersuchungen zur Morphologie und Systematik der Voegel_, 4to., 2 vols. (1888); H.G. Bronn's _Klassen und Ordnungen des Thierreichs_, vol. vi., "Aves," Leipzig, completed 1893 by Gadow; and A. Newton's _Dictionary of Birds_, London, 1896. For the history of the classification of birds see the article ORNITHOLOGY, where also the more important ornithological works are mentioned. EGG, FEATHER (including Moult), MIGRATION, &c., also form separate articles to which reference should be made. In this article (A) the general anatomy of birds is discussed, (B) fossil birds, (C) the geographical distribution of birds, (D) the latest classification of birds.

A. ANATOMY OF BIRDS

1. _Skeleton_.

_Skull._--When W.K. Parker wrote the account of the skull in the article BIRDS for the 9th edition of the _Encyclopaedia Britannica_, he had still to wrestle with the general problem of the composition and evolution of the skull. That chapter of comparative anatomy (together with other anatomical details, for which see the separate articles) is now dealt with in the article SKULL; here only the most avine features are alluded to, and since some of Parker's original illustrations have been retained, the description has been shortened considerably.

One general feature of the adult bird's skull is the almost complete disappearance of the sutures between the bones of the cranium proper, whilst another is the great movability of the whole palatal and other suspensorial apparatus. The occipital condyle (fig. 1) is a single knob, being formed almost wholly by the basioccipital, while the lateral occipitals (often perversely called exoccipitals) take but little share in it. Part of the membranous roof between the supra-occipital and parietal bones frequently remains unossified and presents in the macerated skull a pair of fontanelles. The squamosals form the posterior outer margin of the orbits and are frequently continued into two lateral downward processes across the temporal fossa. One of these, the _processus orbitatis posterior_, often combines with an outgrowth of the alisphenoid, and may be, e.g. in cockatoos, continued forwards to the lacrymal bone, so as to form a complete infraorbital bridge. The posterior, so-called _processus Zygomaticus_ is very variable; in many Galli it encloses a foramen by distally joining the orbital process. The ethmoid frequently appears on the dorsal surface between the frontals. There are three periotic bones (pro-, epi-, opisth-otic). The prooetic encloses between it and the lateral occipital the fenestra ovalis, into which fits the columella of the ear. The epiotic is often small, ossifies irregularly, and fuses with the supra-occipital. The opisthotic lies between the epiotic and the lateral occipital with which it ultimately fuses; in some birds, e.g. in _Larus_, it extends far enough to help to bound the foramen magnum. The basisphenoids are ventrally overlaid, and later on fused with, a pair of membrane bones, the basi-temporals, homologous in part with the parasphenoid of lower vertebrates. They contribute to the formation of the auditory meatus, and of the right and left carotid canals which accompany the eustachian tubes. In many birds the basisphenoids send out a pair of basipterygoid processes by which they articulate with the pterygoids. Dorso-laterally the basisphenoid is joined by the alisphenoid, which forms most of the posterior wall of the orbit. The orbito-sphenoids diverge only posteriorly, otherwise they are practically unpaired and form the median interorbital septum, which is very large in correlation with the extraordinary size of the eyeballs.,

Prefrontal bones are absent; post-frontals are possibly indicated by a frequently occurring separate centre of ossification in the post-orbital process, to which the frontals always contribute. The lacrymal is always present, and perforated by a glandular duct. Attached to it or the neighbouring frontal is often a supraorbital; infraorbitals occur also, attached to the jugal or downward process of the lacrymal. The nasals were used by A.H. Garrod to distinguish the birds as holorhinal (fig. 2) where the anterior margin of the nasal is concave, and schizorhinal where this posterior border of the outer nares is continued backwards into a slit which extends beyond the frontal processes of the premaxilla. Many birds possess a more or less well developed cross-joint in front of the frontals and lacrymals, perhaps best developed in _Anseres_ and _Psittaci_. Owing to this joint the whole upper beak can be moved up and down with extra facility, according to the shoving forwards or backwards of the palato-pterygo-quadrate apparatus which moves sledge-like upon the cranial basis. The premaxilla is always unpaired, but each half has three long processes directed backwards; one fuses with the maxillary bone, another helps to form the anterior part of the palate, while the third, together with its fellow, forms the "culmen" and extends backwards to the frontals, or rather to the ethmoid which there crops up on the surface. The maxillaries (fig. 3) have besides others, a maxillo-palatine process directed inwards in a transverse horizontal direction. The palatines are long, always fused anteriorly with the premaxilla, and frequently with the maxillo-palatine processes; posteriorly they slide upon the presphenoidal rostrum, and articulate in most birds with the pterygoids; they form the greater part of the palatal roof and border the choanae or inner nares. Between these, resting vertically upon the rostrum, appears the vomer; very variable in shape and size, often reduced to a mere trace, as in the Galli, or even absent, broken up into a pair of tiny splints in Pici.

The taxonomic importance of the configurations of the palate was first pointed out by J. de Cornay. T.H. Huxley, in 1868, divided the carinate birds into Dromaeo-, Schizo-, Desmo-, and Aegithognathae, an arrangement which for many years had a considerable influence upon classification. However, subsequent additions and corrections have detracted much from its value, especially when it became understood that the above sub-orders are by no means natural groups. _Dromaeognathae_ have a struthious palate, with a broad vomer meeting in front the broad maxillo-palatal plates, while behind it reaches the pterygoids. The only representatives are the Tinamous. _Schizognathae_, e.g. fowls (fig. 4), pigeons, gulls, plovers, rails and penguins, have the vomer pointed in front while the maxillo-palatines are free, leaving a fissure between the vomer and themselves. The schizognathous formation is doubtless the most primitive, and its representatives form a tolerably natural assembly. _Desmognathae_ (fig. 5) were supposed to have the maxillo-palatines united across the middle line, either directly or by the intermediation of ossifications in the nasal septum. This is a hopeless assembly. Parker and Fuerbringer have demonstrated that desmognathism has been produced in half a dozen ways, implying numerous cases of convergence without any nearer relationship than that they are all derived from some schizognathous group or other. The _Aegithognathae_, meant to comprise the passeres, woodpeckers and swifts, &c., are really schizognathous but with a vomer which is broadly truncated in front.

The remainder of the appendicular skeleton (fig. 6) of the head requires little description. The maxillaries are connected with the distal anterior corner of the quadrate by the thin, splint-like jugal and quadratojugal. The quadrate is invariably a conspicuous bone and movably articulating with the cranium and by a special process with the pterygoid. The mandible is composed of several bones as in reptiles. The os articulare bears on its inner side the inner mandibular process which serves for the insertion of part of the digastric muscle or opener of the mouth; another portion of this muscle is attached to the os angulare, which frequently forms a posterior mandibular process. The greater part of the under-jaw is formed by the right and left dentaries, which in all recent birds are fused together in front. Supra-angular and coronoid splint-bones serve for the insertion of part of the temporal or masseter muscle. Additional splints rest on the inner side of the jaw. Like the crocodiles, birds possess a _siphonium_, i.e. a membranous, or ossified, tube which rises from a pneumatic foramen in the os articulare, on the median side of the articulation, and passes upwards between the quadrate and lateral occipital bone, opening into the cavity of the middle ear.

The _Hyoid apparatus_ is, in its detail, subject to many variations in accord with the very diverse uses to which the tongue of birds is put. It consists of (1) the basihyal variously called copula, or corpus linguae, or unpaired middle portion. (2) The urohyal likewise unpaired, rested ventrally on the larynx. (3) The os entoglossum originally paired, but coalescing into an arrow-headed piece, attached to the anterior end of the basihyal and lodged in the tongue proper. It is homologous with the distal ends of the ceratohyals or ventral elements of the hyoidean or second visceral arch. The dorsal or hyomandibular portion of this same arch is transformed into the auditory chain, ending in the fenestra ovalis. (4) A pair of thyrohyals, homologous with the posterior hyoid horns of mammals, i.e. third visceral or first branchial arch. As the most developed pair in birds they are commonly, although wrongly, called the hyoid horns. They articulate upon facets of the hinder outer corners of the basihyal.

The vertebrae are stereospondylous, the centrum or body and the arch being completely fused into one mass, leaving not even a neuro-central suture. The arch alone sends out processes, viz. the spinous process, the anterior and posterior oblique (commonly called pre- and post-zygapophyses), and the transverse processes. The latter articulate with the tuberculum of the corresponding rib, while the capitulum articulates by a knob on the side of the anterior end of the centrum. In the cervical region the ribs are much reduced, fused with their vertebrae and enclosing the transverse canal or foramen. When the vertebrae are free their centra articulate with each other by complicated joints, exhibiting four types. (1) Amphicoelous; each end of the centrum is concave; this, the lowest condition, is embryonic, but was retained in _Archaeopteryx_ and in the thoracic vertebrae of _Ichthyornis_. (2) Procoelous, concave in front; only in the atlas, for the reception of the occipital condyle. (3) Opisthocoelous, or concave behind, only occasionally found in the thoracic region, e.g. Sphenisci. (4) Heterocoelous (fig. 8) or saddle-shaped; the anterior surface is concave in a transverse, but convex in a vertical direction, which on posterior surface shows the conditions reversed. This is the most perfect arrangement attained by the vertebral column, and is typical of, and restricted to, birds. The intervertebral joints are further complicated by the interposition of a cartilaginous or fibrous pad or ring. This pad varies much; it is morphologically the homologue of the pair of basiventral elements which by their lateral extension give origin to the corresponding ribs. Later those pads fuse with the anterior end of the centrum of the vertebra to which they belong; where the vertebral column is rendered inflexible, the disks are ossified with the centra and all trace of them is lost. Sometimes the pad is reduced to a ventral semi-ring or meniscus; it retains its largest almost original shape and size in the second vertebra, the axis or epistropheus, where it forms a separately ossifying piece which connects, and cooessifies with, the odontoid process (the centrum of the atlas) and the centrum of the second vertebra. Sometimes the ventral portions of these pads form paired or unpaired little ossifications, then generally described as intercentra; such are not uncommon on the tail. The atlas is composed of three pieces; a pair of lateral elements (the right and left dorsal arch pieces) joining above the spinal cord, and a ventral piece equivalent to the first basiventral elements, i.e. serially homologous with the intervertebral pads. In the adults the atlas forms a more or less solid ring. A remnant of the _chorda dorsalis_ and its sheath persists as the _ligamentum suspensorium_ between the central portions of the successive vertebrae.

In birds we distinguish between the following regions of the _axial skeleton_. (1) Cervical vertebrae, or those between the skull and the first vertebra which is connected with the sternum by a pair of complete ribs. The last 1 to 5 of these vertebrae have movable ribs which do not reach the sternum, and are called cervico-dorsals. (2) Dorsals, those which begin with the first thoracic rib, and end at the last that is not fused with the ilium. The term "lumbar" vertebrae is inapplicable to birds. (3) Pelvic, all those which are fused with the iliac portion of the pelvis, generally a considerable number. (4) Caudal, those which are not connected with the pelvis. It is to be noted that often no absolute line of demarcation can be drawn in regard to these regions, their definitions being rather convenient than morphological.

In comparison with all other vertebrates the number of neck-vertebrae of the birds is considerably increased; the lowest number, 14 to 15, is that of most Passeres and many other Coraciomorphae; the largest numbers, 20 or 21, are found in the ostrich, 23 in _Cygnus olor_ and 25 in the black swan. Dorsal vertebrae frequently have a ventral outgrowth of the centrum; these hypapophyses may be simple vertical blades, _|_-shaped, or paired knobs; they serve for the attachment of the thoracic origin of the longus collianticus muscle, reaching their greatest development in Sphenisci and Colymbidae. In many birds some of the thoracic vertebrae are more or less cooessified, in most pigeons for instance the 15th to 17th; in most Galli the last cervical and the next three or four thoracics are coalesced, &c. The pelvic vertebrae include of course the sacrum. There are only two or three vertebrae which are equivalent to those of the reptiles; these true sacrals are situated in a level just behind the acetabulum; as a rule between these two primary sacral vertebrae issues the last of the spinal nerves which contributes to the composition of the sciadic plexus. These true sacrals alone are connected with the ilium by processes which are really equivalent to modified ribs; but the pelvis of birds extends considerably farther forwards and backwards, gradually coming into contact with other vertebrae, which in various ways send out connecting transverse processes or buttresses, and thus become pre- and post-sacral vertebrae (fig. 9). The most anterior part of the ilium often overlaps one or more short lumbar ribs and fuses with them, or even a long, complete thoracic rib. Similarly during the growth of the bird the posterior end of the ilium connects itself with the transverse processes of vertebrae which were originally free, thus transforming them from caudals into secondary post-sacrals. Individual, specific and generic variations are frequent.

The last six or seven caudal vertebrae coalesce into the pygostyle, an upright blade which carries the rectrices. Such a pygostyle is absent in _Archaeopteryx, Hesperornis, Tinami_ and _Ratitae_, but it occurs individually in old specimens of the ostrich and the kiwi. In _Ichthyornis_ it is very small. In all the _Neornithes_ the total number of caudal vertebrae, inclusive of those which coalesce, is reduced to at least 13.

_Sternum_ (figs. 10 and 11).--Characteristic features of the sternum are the following. There is a well-marked _processus lateralis anterior_ (the right and left together equivalent to the mammalian manubrium), which is the product of two or three ribs, the dorsal parts of which reduced ribs remain as cervico-dorsal ribs. Then follows the rib-bearing portion and then the _processus lateralis posterior_; this also is the product of ribs, consequently the right and left processes together are equivalent to the xiphoid process or xiphisternum of the mammals. The lateral process in most birds sends out an outgrowth, directed out and upwards, overlapping some of the ribs, the _processus obliquus_. The median and posterior extension of the body of the sternum is a direct outgrowth of the latter, therefore called meta-sternum. The anterior margin of the sternum, between the right and left anterior lateral processes receives in sockets the feet of the coracoids. Between them arises a median crest, which varies much in extent and composition, and is of considerable taxonomic value. It is represented either by a _spina interna_ or by a _spina externa_, or by both, or they join to form a _spina communis_ which is often very large and sometimes ends in a bifurcation. Eventually, when the right and left feet of the coracoids overlap each other, the anterior sternal spine contains a foramen. The keel, or _carina sterni_, is formed as a direct cartilaginous outgrowth of the body of the sternum, ossifying from a special centre. This keel is much reduced in the New Zealand parrot, _Stringops_, less in various flightless rails, in the dodo and solitaire. It is absent in the Ratitae, which from this feature have received their name, but considerable traces of a cartilaginous keel occur in the embryo of the ostrich, showing undeniably that the absence of a keel in the recent bird is not a primitive, fundamental feature. The keel has been lost, and is being lost, at various epochs and by various groups of birds. The swimming _Hesperornis_ (see ODONTORNITHES) was also devoid of such a structure. In many birds the spaces between the meta-sternum and the posterior processes and again the spaces between this and the oblique process are filled up by proceeding ossification and either remain as notches, or as fenestrae, or they are completely abolished so that the breastbone is turned into one solid more or less oblong plate.

_Shoulder Girdle._--Scapula, coracoid and clavicle, meet to form the foramen triosseum, through which passes the tendon of the _supracoracoideus_, or _subclavius_ muscle to the _tuberculum superius_ of the humerus. The coracoid is one of the most characteristic bones of the bird's skeleton. Its upper end forms the acrocoracoid process, against the inner surface of which leans the proximal portion of the clavicle. From the inner side of the neck of the coracoid arises the precoracoidal process, the remnant of the precoracoid. Only in the ostrich this element is almost typically complete, although soon fused at either end with the coracoid. Near the base of the precoracoidal process is a small foramen for the passage of the _nervus supracoracoideus_. In most birds the feet of the coracoids do not touch each other; in some groups they meet, in others one overlaps the other, the right lying ventrally upon the left. The scapula is sabre-shaped, and extends backwards over the ribs, lying almost parallel to the vertebral column. This is a peculiar character of all birds. The clavicles, when united, as usual, form the furcula; mostly the distal median portion is drawn out into a hypocleidium of various shape. Often it reaches the keel of the sternum, with subsequent syndosmosis or even synostosis, e.g. in the gannet. In birds of various groups the clavicles are more or less degenerated, the reduction beginning at the distal end. This condition occurs in the Ratitae as well as in the well-flying _Platyrcecinae_ amongst parrots.

The _fore-limb_ or _wing_ (fig. 12); highly specialized for flight, which, initiated and made possible mainly by the strong development of quill-feathers, has turned the wing into a unique organ. The humerus with its crests, ridges and processes, presents so many modifications characteristic of the various groups of birds, that its configuration alone is not only of considerable taxonomic value but that almost any genus, excepting, of course, those of Passeres, can be "spotted" by a close examination and comparison of this bone. When the wing is folded the long glenoid surface of the head of the humerus is bordered above by the _tuberculum externum_ or _superius_, in the middle and below by the _tuberculum medium_ or _inferius_ for the insertion of the _coraco-brachialis posterior_ muscle. From the outer tuberculum extends the large _crista superior_ (insertion of _pectoralis major_ and of _deltoideus major_ muscles). The ventral portion of the neck is formed by the strong _crista inferior_, on the median side of which is the deep _fossa subtrochanterica_ by which air sacs enter the humerus. On the outer side of the humerus between the head and the _crista inferior_ is a groove lodging one of the coraco-humeral ligaments. The distal end of the humerus ends in a trochlea, with a larger knob for the ulna and a smaller oval knob for the radius. Above this knob is often present an ectepicondylar process whence arise the tendons of the ulnar and radial flexors. The radius is the straighter and more slender of the two forearm bones. Its proximal end forms a shallow cup for articulation with the outer condyle of the humerus; the distal end bears a knob which fits into the radial carpal. The ulna is curved and rather stout; it articulates with both carpal bones; the cubital quills often cause rugosities on its dorsal surface. Of wrist-bones only two remain in the adult bird; the original distal carpals coalesce with the proximal end of the metacarpals. These are reduced, in all birds, to three, but traces of the fourth have been observed in embryos. The first metacarpal is short and fuses throughout its length with the second. This and the third are much longer and fuse together at their upper and distal ends, leaving as a rule a space between the shafts. The pollex and the third finger are as a rule reduced to one phalanx each, while the index still has two. The first and second fingers frequently carry a little claw. The greatest reduction of the hand-skeleton is met with in _Dromaeus_ and in _Apteryx_, which retain only the index finger. It is of importance for our understanding of the position of the Ratitae in the system, that the wing-skeleton of the ostrich and rhea is an exact repetition of that of typical flying birds; the bones are much more slender, and the muscles are considerably reduced in strength also to a lesser extent in numbers, but the total length of the wing of an ostrich or a rhea is actually and comparatively enormous. Starting with the kiwi and cassowary, people have got into the habit of confounding flightless with wingless conditions. It is absolutely certain that the wings of the Ratitae bear the strongest testimony that they are the descendants of typical flying birds.

The _pelvis_ (fig. 13), consisting of the sacrum (already described) and the pelvic arch, namely ilium, ischium and pubis, it follows that only birds and mammals possess a pelvis proper, whilst such is entirely absent in the Amphibia and in reptiles with the exception of some of the Dinosaurs. The ventral inner margin of the preacetabular portion of the ilium is attached to the pre-sacral vertebrae, whilst the inner and dorsal margin of the postacetabular portion is attached to the primary sacral and the postsacral vertebrae. In rare cases the right and left preacetabular blades fuse with each other above the spinous processes. In front of the acetabulum a thick process of the ilium descends to meet the pubis, and a similar process behind meets the ischium. The acetabulum is completely surrounded by these three bones, but its cup always retains an open foramen; from its posterior rim arises the strong antitrochanter. The ischium and postacetabular ilium originally enclose the ischiadic notch or _incisura ischiadica_. This primitive condition occurs only in the Odontornithes (q.v.), Ratitae and Tinami; in all others this notch becomes converted into a _foramen ischiadicum_, through which pass the big stems of the ischiadic nerves and most of the blood-vessels of the hind-limb. The pubis consists of a short anterior portion (_spina pubica_ or pectineal process, homologous with the prepubic process of Dinosaurs) and the long and slender pubis proper (equivalent to the _processus lateralis pubis_ of most reptiles). The shaft of the pubis runs parallel with that of the ischium, with which it is connected by a short ligamentous or bony bridge; this cuts off from the long _incisura pubo-ischiadica_ a proximal portion, the _foramen obturatum_, for the passage of the obturator nerve. Only in the ostrich the distal ends of the pubes meet, forming a dagger-shaped symphysis, which is curved forwards. The pectineal process is variable; it may grow entirely from the pubis, or both pubis and ilium partake of its formation, or lastly its pubic portion may be lost and the process is entirely formed by the ilium. It is largest in the Galli and some of the Cuculi, in others it is hardly indicated. It served originally for the origin of the ambiens muscle (see _Muscular System_ below); shifting or disappearance of this muscle, of course, influences the process.

_The Hind Limb._--The femur often possesses a well visible pneumatic foramen on the median side of the proximal end of its shaft. The inner condyle, the intercondylar sulcus, and a portion only of its outer condyle, articulate with corresponding facets of the tibia. The outer condyle articulates mainly with the fibula. There is a patella, intercalated in the tendon of the _femori-tibialis_ or _extensor cruris_ muscle. In _Colymbus_ the patella is reduced to a small ossicle, its function being taken by the greatly developed pyramidal _processus tibialis anterior_; in _Podiceps_ and _Hesperornis_ the patella itself is large and pyramidal. The distal half of the fibula is very slender and normally does not reach the ankle-joint; it is attached to the peroneal ridge of the tibia. On the anterior side of the tibia, is the intercondylar sulcus, which is crossed by an oblique bridge of tendon or bone, acting as a pulley for the tendon of the _extensor digitorum communis_ muscle. The condyles of the tibia are in reality not parts of this bone, but are the three proximal tarsalia which fuse together and with the distal end of the tibia. The distal tarsalia likewise fuse together, and then on to the upper ends of the metatarsals; the _tarsale centrale_ remains sometimes as a separate osseous nodule, buried in the inter-articular pad. Consequently the ankle-joint of birds is absolutely cruro-tarsal and tarso-metatarsal, i.e. intertarsal, an arrangement absolutely diagnostic of birds if it did not also occur in some of the Dinosaurs. Of the metatarsals the fifth occurs as an embryonic vestige near the joint; the first is reduced to its distal portion, and is, with the hallux, shoved on to the inner and posterior side of the foot, at least in the majority of birds. The three middle metatarsals become fused together into a cannon bone; the upper part of the third middle metatarsal projects behind and forms the so-called hypotarsus, which in various ways, characteristic of the different groups of birds (with one or more sulci, grooved or perforated), acts as guiding pulley to the tendons of the flexor muscles of the toes. Normally the four toes have two, three, four and five phalanges respectively, but in _Cypselus_ the number is reduced to three in the front toes. Reduction of the number of toes (the fifth shows no traces whatever, not even in _Archaeopteryx_) begins with the hallux, which is completely or partly absent in many birds; the second toe is absent in _Struthio_ only. The short feet of the penguins are quite plantigrade, in adaptation to which habit the metatarsals lie in one plane and are incompletely co-ossified, thus presenting a pseudo-primitive condition.

LITERATURE.--Only a mere fraction of the enormous literature dealing with the skeleton of birds can here be mentioned.

M.E. Alix _Essai sur l'appareil locomoteur des oiseaux_ (Paris, 1874); E. Blanchard, "Recherches sur les caracteres osteologiques des oiseaux appliquees a la classification," _Ann. Sci. Nat. Ser._ iv., t. xi.; W. Dames, "Ueber Brustbein Schulter- und Beckenguertel der Archaeopteryx," _Math. Naturw. Mitsh._, Berlin, vii., 1897, pp. 476-492; T.C. Eyton, _Osteologia avium_ (London, 1858-1881), with many plates; C. Gegenbaur, _Untersuch. z. vergl. Anat. d. Wirbelthiere, I. Carpus und Tarsus, II. Schultergurtel_ (Leipzig, 1864-1865); P. Harting, _L'Appareil episternal des oiseaux_ (Utrecht, 1864); T.H. Huxley, "On the Classification of Birds and on the Taxonomic Value of the Modifications of certain of the Cranial Bones..." _P.Z.S._, 1867; G. Jaeger, "Das Wirbelkorpergelenk der Voegel," _Sitzb. K. Ak. Wiss._, Wien, xxxiii., 1858; A. Johnson, "On the Development of the Pelvic Girdle and Skeleton of the Hind-limb in the Chick," _Q.J.M.S._, xxiii., 1883, pp. 399-411; K.F. Kessler, "Osteologie der Vogelfuesse," _Bull. Soc. Imp. Nat._, Moscow, xiv., 1841; B. Lindsay, "On the Avian Sternum," _P.Z.S._, 1885; E. Mehnert, "Entwickelung des Ospelvis der Voegel," _Morph. Jahrb._, xiii., 1877; A.B. Meyer, _Abbildungen van Voegel-Skeletten_ (Dresden, 1879); St G. Mivart, "On the Axial Skeleton of the Ostrich, Struthionidae, Pelecanidae," _Trans. Zool. Soc._ viii., 1874; x., 1877; E.S. Morse, "On the Carpus and Tarsus of Birds," _Ann. Lyc. N.H._, New York, x., 1874; J.S. Parker, "Observations on the Anatomy and Development of Apteryx," _Phil. Trans._, 1890, pp. 1-110, 17 pls.; W. K. Parker, numerous papers in _Trans. L.S., R.S._ and _Z.S._, e.g. "Osteology of Gallinaceous Birds," _T.Z.S._, v., 1863; "Rhinochetus," _ibid._ vi.; "Skull of Aegithognathous Birds," _ibid._, x., 1878; "Skull in the Ostrich Tribe," _Phil. Trans._ vol. 156, 1866; "Skull of Common Fowl," _ibid._ vol. 159, 1870; "Skull of Picidae," _T. Linn. Soc._, 1875; "Monograph on the Structure and Development of the Shoulder-girdle and Sternum," _Ray Soc._ London, 1868; W.P. Pycraft, "On the Morphology and Phylogeny of the Palaeognathae (_Ratitae_ and _Crypturi_) and Neognathae," _Trans. Zool. Soc._ xv., 1900, pp. 149-290, pis. 42-45; id. "Some points in the morphology of the Palate of the Neognathae," _T. Linn. Soc._ 28, pp. 343-357, pls. 31-32; P. Suschkin, "Zur Morphologie des Vogelskelets. I. Schaedel von Tinnunculus," _Mem. Soc., Moscow_, xvi., 1900, pp. 1-63, pls.

2. _Muscular System._

Of the muscles of the stem or axis, those of the neck and tail are well-developed and specialized, while those of the lower back are more or less reduced, or even completely degenerated owing to the rigidity of this region, brought about by the great antero-posterior extent of the pelvis.

The muscles of the limbs show a great amount of specialization, away from the fundamental reptilian and mammalian conditions. The muscles of the fore limbs are most aberrant, but at the same time more uniformly developed than those of the hinder extremities. The reasons are obvious. The whole wing is a unique modification, deeply affecting the skeletal, muscular and tegumentary structures, but fluttering, skimming, sailing, soaring are motions much more akin to one another than climbing and grasping, running, scratching, paddling and wading. The modifications of the hind-limbs are in fact many times greater (such as extremely long legs, with four, three or only two toes; very short legs, almost incapable of walking, with all four toes directed forwards, or two or one backwards, and two or more connected and therefore bound to act together, in various ways). Thus it has come to pass that the muscles of the hind limbs are, like their framework, more easily compared with those of reptiles and mammals than are the wings, whilst within the class of birds they show an enormous amount of variation in direct correlation with their manifold requirements. The only really aberrant modifications of the wing-muscles are found in the Ratitae, where they are, however, all easily explained by reduction, and in the penguins, where the wings are greatly specialized into blades for rowing with screw-like motions.

The wing of the bird is folded in a unique way, namely, the radius parallel with the humerus, and the whole wrist and hand with their ulnar side against the ulna; upper and forearm in a state of supination, the hand in that of strong abduction. Dorsal and ventral bending, even in the extended wing, is almost impossible. Consequently only a few of the original extensor muscles have been preserved, but these are much modified into very independent organs, notably the _extensor metacarpi radialis longus_, the _ext. metac. ulnaris_ and the two _radio_- and _ulnari-metacarpi_ muscles, all of which are inserted upon the metacarpus by means of long tendons. The chief muscular mass, arising from the sternum in the shape of a U, is the _pectoralis_ muscle; its fibres converge into a strong tendon, which is inserted upon the greater tubercle and upper crest of the humerus, which it depresses and slightly rotates forwards during the downstroke. This great muscle covers completely the _supracoracoideus_, generally described as the second pectoral, or _subclavius_ muscle, in reality homologous with the mammalian _supraspinatus_ muscle. This arises mostly from the angle formed by the keel with the body of the sternum, passes by a strong tendon through the _foramen triosseum_, and is inserted upon the upper tubercle of the humeral crest, which it rotates and abducts. The extent of the origin of this muscle from the sternum, on which it leaves converging, parallel or diverging impressions, is of some taxonomic value.

Much labour has been bestowed by A.H. Garrod and Max Fuerbringer upon the investigation of the variations of the inserting tendons of the patagial muscles (fig. 14), mainly from a taxonomic point of view. The _propatagialis longus_ muscle is composed of slips from the deltoid, pectoral, biceps and _cucullaris_ muscles. Its strong belly originates near the shoulder joint from clavicle, coracoid and scapula. Its elastic tendon runs directly to the carpus, forming thereby the outer margin of the anterior patagium, or fold of skin between the upper and forearm, which it serves to extend, together with the _propatagialis brevis_ muscle. This runs down the anterior and outer side of the upper arm, and is attached to the proximal tendon of the _extensor metacarpi radialis longus_, a little below the outer condyle of the humerus. In most birds the tendon is split into several portions, one of which is often attached to the outer side of the ulna, below the elbow joint, while others are in variable but characteristic ways connected with similar slips of the _propatagialis longus_. The posterior patagium, the fold between trunk and inner surface of the upper arm, is stretched by the _metapatagialis_ muscle, which is composed of slips from the _serratus, superficialis, latissimus dorsi_ and the _expansor secundariorum muscles_. This, the stretcher of the cubital quills, is a very interesting muscle. Arising as a long tendon from the sterno-scapular ligament, it passes the axilla by means of a fibrous pulley, accompanies the axillary vessels and nerves along the humerus, and is inserted by a few fleshy fibres on the base of the last two or three cubital quills. Here, alone, at the distal portion of the tendon, occur muscular fibres, but these are unstriped, belonging to the category of cutaneous muscles. We have here the interesting fact that a muscle (portion of the _triceps humeri_ of the reptiles) has been reduced to a tendon, which in a secondary way has become connected with cutaneous muscles, which, when strongly developed, represent its belly.

The _flexor digitorum sublimis_ muscle arises fleshy from the long elastic band which extends from the inner humeral condyle along the ventral surface of the ulna to the ulnar carpal bone, over which the tendon runs to insert itself on the radial anterior side of the first phalanx of the second digit. Owing to the elasticity of the humerocarpal band the wing remains closed without any special muscular exertion, while, when the wing is extended, this band assists in keeping it taut. The arm-muscles have been studied in an absolutely exhaustive manner by Fuerbringer, who in his monumental work has tabulated and then scrutinized the chief characters of fourteen selected muscles. The results are as interesting from a morphological point of view (showing the subtle and gradual modifications of these organs in their various adaptations), as they are sparse in taxonomic value, far less satisfactory than are those of the hind-limb. He was, however, the first to show clearly that the Ratitae are the retrograde descendants of flying ancestors, that the various groups of surviving Ratitae are, as such, a polyphyletic group, and he has gone fully into the interesting question of the development and subsequent loss of the power of flight, a loss which has taken place not only in different orders of birds but also at various geological periods, and is still taking place. Very important are also the investigations which show how, for instance in such fundamentally different groups as petrels and gulls, similar bionomic conditions have produced step by step a marvellously close convergence, not only in general appearance, but even in many details of structure.

Of the muscles of the hind-limbs likewise only a few can be mentioned. The _ambiens_ muscle, long and spindle-shaped, lying immediately beneath the skin, extending from the pectineal process or ilio-pubic spine to the knee, is the most median of the muscles of the thigh. When typically developed its long tendon passes the knee-joint, turning towards its outer side, and lastly, without being anywhere attached to the knee, it forms one of the heads of the _flexor perforatus digit_, ii. or iii. One of the functions of this peculiar muscle (which is similarly developed in crocodiles, but absent, or not differentiated from the ilio-tibial and ilio-femoral mass, in other vertebrates) is that its contraction helps to close the second and third toes. Too much has been made of this feature since Sir R. Owen (_Cyclop. Anat. Phys_. i. p. 296, 1835), following G.A. Borelli (_De motu animalium_, Rome, 1680), explained that birds are enabled to grasp the twig on which they rest whilst sleeping, without having to make any muscular exertion, because the weight of the body bends the knee and ankle-joints, over both of which pass the tendons of this compound muscle. There are many perching birds, e.g. all the Passeres, which do not possess this muscle at all, whilst many of those which have it fully developed, e.g. Anseres, can hardly be said to "perch."

Garrod went so far as to divide all the birds into _Homalogonatae_ and _Anomalogonatae_, according to the presence or absence of the ambiens muscle. This resulted in a failure. To appreciate this, it is sufficient to enumerate the birds without the critical muscle: _Passeriformes_ and _Coraciiformes_, without exception; _Ardeae_ and _Podiceps_; lastly various genera of storks, pigeons, parrots, petrels and auks. The loss has taken place, and still takes place, independently in widely different groups. It follows, first, that the absence of this muscle does not always indicate relationship; secondly that we can derive birds that are without it from a group which still possess it, but not vice versa. The absence of the ambiens muscle in all owls, which apparently use their feet in the same way as the _Accipitres_ (all of which possess it), indicates that owls are not developed from the latter, but from a group which, like the other _Coraciiformes_, had already lost their muscle.

Garrod further attributed much taxonomic value to the _caudilio-femoralis_ muscle (fig. 15). This, when fully developed, consists of two parts, but inserted by a single ribbon-like tendon upon the hinder surface of the femur, near the end of its first third; the caudal part, _femoro-caudalis_, expressed by Garrod by the symbol _A_, arises from transverse processes of the tail; the iliac part (_accessoro-femoro-caudal_ of Garrod, with the symbol _B_), arises mostly from the outer surface of the postacetabular ilium. Of course this double-headed condition is the more primitive, and as such exists in most nidifugous birds, but in many of these, as well as in many nidicolous birds, either the caudal or the iliac head is absent, and in a very few (_Cancroma, Dicholophus, Steatornis_ and some _Cathartes_) the whole muscle is absent. The _caud-ilio flexorius_ (_semitendinosus_ of most authors) arises from the transverse processes of the tail, and from the distal half of the postacetabular ilium, thence passing as a broad ribbon to the popliteal region, where it splits into two portions. One of these, broad and fleshy, is inserted upon the posterior surface of the distal third of the femur. This portion, morphologically the original, was named the "accessory semitendinosus" with the symbol _Y_; the other portion descends on the hinder aspect of the leg and joins the fascia of the inner femoral head of the _gastrocnemius_ muscle. In many birds the insertion is shifted from the femur to the neck of the tibia, in which case the "accessory head" is said to be absent, a condition expressed by Garrod by the symbol _X_. By combining the four symbols _A, B, X, Y_, according to their presence or absence, Garrod got a considerable number of formulae, each of which was overruled, so to speak, by the two categories of the presence or absence of the _ambiens_ muscle. It needs hardly to be pointed out why such a purely mechanical scheme was doomed to failure. Its author, with a considerable mathematical and mechanical bias, reckoned entirely with the quantity, not with the quality of his units, and relied almost implicitly upon his formulae. It is, however, fair to state that his system was not built entirely upon these muscular variations, but rather upon a more laborious combination of anatomical characters, which were so selected that they presumably could not stand in direct correlation with each other, notably the oil-gland, caeca, carotids, nasal bones and above all, the muscles of the thigh. He was, indeed, the first to show clearly the relationship of the heron-like birds with the Steganopodes; of stork-like birds with the American vultures; the great difference between the latter and the other birds of prey; the connexion of the gulls and auks with the plovers, and that of the sand-grouse with the pigeons--discoveries expressed in the new terms of the orders Ciconiiformes and Charadriiformes. These are instances, now well understood, that almost every organic system, even when studied by itself, may yield valuable indications as to the natural affinities of the various groups of birds. That Garrod has so very much advanced the classification of birds is ultimately due to his comprehensive anatomical knowledge and general insight.

To return to these thigh muscles. The most primitive combination, ambiens and _A B X Y_, is the most common; next follows that of _A X Y_, meaning the reduction of _B_, i.e. the iliac portion of the _caud-ilio-femoralis_; _A B X_ and _B X Y_ are less common; _A X_ and _X Y_ are rare and occur only in smaller groups, as in subfamilies or genera; _B X_ occurs only in _Podiceps_. But the greatest reduction, with only _A_ remaining, is characteristic of such a heterogeneous assembly as Accipitres, Cypselidae. Trochilidae, Striges and Fregata. This fact alone is sufficient proof that these conditions, or rather reductions, have been acquired independently of the various groups. _A B Y_, _A Y_, _A B_, _X Y_ and _B_ do not occur at all, some of them for obvious reasons. Occasionally there is an instructive progressive evolution expressed in these formula; for instance _Phaethon_, in various other respects the lowest of the Steganopodes, has _A X Y_, _Sula_ and _Phalacrocorax_ have _A X_, _Fregata_, the most specialized of these birds, has arrived at the reduced formula _A_. Further, the combinations _B X Y_ and _A X Y_ cannot be derived from each other, but both directly from _A B X Y_ in two different directions. Keeping this in mind, we may fairly conclude that the flamingo with _B X Y_ points to an ancestral condition _A B X Y_, which is still represented by _Platalea_ and _Ibis_, whilst the other storks proper have taken a different line, leading to _A X Y_.

LITERATURE.--Well nigh complete lists of the enormous myological literature are contained in Fuerbringer's _Untersuchungen zur Morphologie und Systematik der Voegel_, and in Gadow's vol. _Voegel_ of Bronn's _Klassen und Ordnungen des Tierreichs_. Only a few papers and works can be mentioned here, with the remark that few authors have paid attention to the all-important innervation of the muscles. A. Carlsson, _Beitraege zur Kenntniss der Anatomieder Schiwmmvoegel_; K. Svensk, _Vet. Ak. Handlinger. J.G._ No. 3 (1884); A. Alix, _Essai sur l'appareil locomoteur des oiseaux_ (Paris, 1874); H. Gadow, _Zur vergl. Anat. der Muskulatur des Beckens und der hinteren Gliedmasse der Ratiten_,4 deg. (Jena, 1880); A.H. Garrod, "On Certain Muscles of the Thigh of Birds and on their value in Classification," _P.Z.S._, 1873, pp. 624-644; 1874, pp. 111-123. Other papers by Garrod, 1875, pp. 339-348 (deep planter tendons); 1876, pp. 506-519 (wing-muscles of Passeres), &c.; J.G. de Man, _Vergelijkende myologische en neurologische Studien over Amphibien en Voegels_ (Leiden, 1873), (_Corvidae_); A. Milne-Edwards, _Recherches anatomiques et paleontologiques pour servir a l'histoire des oiseaux fossiles de la France_ (Paris, 1867-1868), tom. i. pls. ix.-x. (_Aquila_ and _Gallus_); R. Owen, article "Aves," Todds' _Cydopaed. of Anat. and Phys._ i. (London, 1835); "On the Anatomy of the Southern _Apteryx_," _Trans. Zool. Soc._, iii., 1849; A. Quennerstedt, "Studier i foglarnas anatomi," _Lunds Univers. Aarsk._, ix., 1872 (hind-limb of swimming birds); G. Rolleston, "On the Homologies of Certain Muscles connected with the Shoulder-joint," _Trans. Linn. Soc._, xxvi., 1868; R.W. Shufeldt, _The Myology of the Raven_ (London, 1891); M. Watson, "Report on the Anatomy of the _Spheniscidae_," _Challenger Reports_, 1883.

3. _Nervous System._

_Brain._--The more characteristic features of the bird's brain show clearly a further development of the reptilian type, not always terminal features in a direct line, but rather side-departures, sometimes even a secondary sinking to a lower level, and in almost every case in a direction away from those fundamentally reptilian lines which have led to the characters typical of, and peculiar to, the mammals.

The forebrain forms the bulk of the whole brain, but the large size of the hemispheres is due to the greater development of the basal and lateral portions (_pedunculi cerebri_ and _corpora striata_), while the pallium (the portion external to the lateral ventricles) is thin, and restricted to the median side of each hemisphere. As a direct result of this undoubtedly secondary reduction of the pallium--due to the excessive preponderance of the basal and lateral parts--the corpus callosum (i.e. the transverse commissure of the right and left pallium) is in birds reduced to a narrow flat bundle of a few white fibres; it is situated immediately above and behind the much stronger anterior commissure, i.e. the connexion between the corpora striata, or chief remaining part of the hemispheres. Owing to the small size of the olfactory lobes the anterior arms of the latter commissure are wanting. There is very little grey matter in the cortex of the hemispheres, the surface of which is devoid of convolutions, mostly quite smooth; in others, for instance pigeons, fowls and birds of prey, a very slight furrow might be compared with the Sylvian fissure.

The Thalamencephalon is much reduced. The epiphysis, or pineal body, is quite as degenerate as in mammals, although still forming a long stalk as in reptiles. In birds, this stalk consists entirely of blood-vessels, which in the adult enclose no terminal vesicle, and fuse with the membranous linings of the skull. The midbrain is represented chiefly by the optic lobes, the cortex of which alone is homologous with the _corpora quadragemina_ of the mammals. Their transverse dorsal connexion is the posterior commissure; otherwise the whole roof portion of the midbrain is reduced to a thin membrane, continuous with that which covers the Sylvian aqueduct, and this ventricle sends a lateral cavity into each optic lobe, as is the case in reptiles. The right and left lobes themselves are rent asunder (so to speak), so that they are freely visible from above, filling the corners formed by the hemispheres and the cerebellum. The latter is, in comparison with mammals; represented by its middle portion only, the _vermis_; in a sagittal section it shows an extremely well developed _arbor vitae_, produced by the transverse, repeated folding of the whole organ. In comparison with reptiles the cerebellum of birds shows high development. Forwards it covers, and has driven asunder, the optic lobes; backwards it hides the much shortened medulla oblongata.

Several futile attempts have been made to draw conclusions as to the intelligence of various birds, from comparison of the weight of the whole brain with that of the body, or the weight of the hemispheres with that of other parts of the central nervous system.

The _brachial plexus_ is formed by four or five of the lowest cervical nerves; the last nerve of this plexus often marks the boundary of the cervical and thoracic vertebrae. The composition of the plexus varies much, not only in different species, but even individually. The most careful observations are those by Fuerbringer. The serial number of these nerves depends chiefly upon the length of the neck, the extremes being represented by _Cypselus_ (10th-14th cervical) and _Cygnus_ (22nd-24th), the usual numbers of the common fowl being the 13th-17th nerves.

The _Crural Plexus_ is divided into a crural, ischiadic and pubic portion. The first is generally composed of three nerves, the hindmost of which, the _furcalis_, issues in most birds between the last two lumbo-sacral vertebrae, and then divides, one half going to the crural, the other to the sciatic portions. The _obturatorius_ nerve invariably comes from the two main stems of the crural. The ischiadic portion consists generally of five or six nerves, which leave the pelvis as one thick system through the ilio-ischiadic foramen. The last nerve which contributes to the ischiadic plexus leaves the spinal column in most birds either between the two primary sacral vertebrae, or just below the hindmost of them, and sends a branch to the pubic portion which is composed of post-ischiadic nerves, partly imbedded in the kidneys, and innervates the ventral muscles between the tail and pubis, together with those of the cloaca and copulatory organs.

The _Sympathetic System_ forms a chain on either side of the vertebral column. In the region of the neck lateral strands pass through the transverse canal of the cervical vertebrae; but from the thoracic region onwards, where the cardiac branch to the heart is given off, each strand is double and the basal ganglia are successively connected with the next by a branch which runs ventrally over the capitulum of the rib, and by another which passes directly through the foramen or space formed between capitulum and tuberculum. In the pelvic region, from about the level of the posterior end of the ischiadic plexus, the strand of each side becomes single again, passing ventrally over the transverse processes. Lastly, towards the caudal region the right and left strands approach and anastomose, eventually coalescing in the mid line.

LITERATURE.--A. Bumm, "Das Grosshirn der Voegel," _Zeitschr. wiss. Zool._, 38, 1883, pp. 430-466, pls. 24-25; F. Leuret and P. Gratiolet, _Anatomie comparee du systeme nerveux_ (Paris, 1839-1857), with atlas; A. Meckel, "Anatomie des Gehirns der Voegel," in _Meckel's Archiv f. Physiol._ vol. ii.; H.F. Osborn, "The Origin of the Corpus Callosum, a contribution upon the Cerebral Commissures of the Vertebrata," _Morphol. Jahrbuch_, 1886, xii. pp. 223-251, pls. 13-14; M.A. Schulgin, "Lobi optici der Voegel," _Zool. Anzeig._ iv. pp. 277 and 303; E.R.A. Serres, _Anatomie comparee du cerveau_ (Paris, 1824, 4 pls.); L. Stieda, "Studien uber das centrale Nervensystem der Voegel und Saeugethiere," _Zeitschr. wiss. Zool._ xix., 1869, pp. 1-92, pls.; J. Swan, _Illustrations of the Comparative Anatomy of the Nervous System_ (London, 1835, 4to, with plates).

Concerning the spinal nerves and their plexus: H. v. Jhering, _Das peripherische Nervensystem der Wirbeltiere_ (Leipzig, 1871); W.A. Haswell, "Notes on the Anatomy of Birds," _Proc. Linn. Soc. N.S.W._ iii., 1879; M. Fuerbringer, "Zur Lehre von den Umbildungen der Nervenplexus," _Morph. Jahrb._ v., 1879, p. 358.

4. _Organs of Sense._

The _Eye_ is essentially reptilian, but in sharpness of vision, power and quickness of accommodation it surpasses that of the mammals. The eyeball, instead of being globular, resembles rather the tube of a short and thick opera-glass.

The anterior half of the sclerotic is composed of a ring of some ten to seventeen cartilaginous or bony scales which partly overlap each other. Another cartilage or ossification, the posterior sclerotic ring, occurs within the walls of the posterior portion of the cup, and surrounds, especially in the Pici and in the Passeres, the entrance of the optic nerve. The iris is in most young birds at first brown or dull-coloured, but with maturity attains often very bright tints which add considerably to the charm of the bird; sexual dimorphism is in this respect of common occurrence. The iris contains a sphincter and a dilator muscle; the former, supplied by branches from the _oculomotorius_ nerve, is under control of the will, whilst the dilator fibres belong to the sympathetic system. When fully dilated, the pupil is round in all birds; when contracted it is usually round, rarely oval as in the fowl. From near the entrance of the optic nerve, through the original choroidal fissure, arises the much-folded pecten, deeply pigmented and very vascular, far into the vitreous humour. The number of its folds varies considerably, from three in _Caprimulgus_ to nearly thirty in crow (_Corvus_). _Apteryx_, which since Owen has generally been stated to be devoid of such an organ, likewise possesses a pecten; its base is, however, trumpet-shaped, covers almost the whole of the optic disk, and extends nearly to the lens in the shape of a thick, densely pigmented cone, without any plications, resembling in these respects the pecten of many Lacertilia (see G.L. Johnson, _Phil. Trans._, 1901, p. 54). In the retina the cones prevail in numbers over the rods as in the mammals, and their tips contain, as in other Sauropsida, coloured drops of oil, mostly red or yellow. Near the posterior pole of the fundus, but somewhat excentrically placed towards the temporal or outer side, is the _fovea centralis_, a slight depression in the retina, composed almost entirely of cones, the spot of most acute vision. Many birds possess besides this temporal fovea a second fovea nearer the nasal side. It is supposed that the latter serves monocular, the other the binocular vision, most birds being able to converge their eyes upon one spot. Consequently the whole field of vision of these birds possesses three points where vision is most acute. It may here be remembered that of the mammalia man and monkeys alone are capable of convergence, and have a circumscribed macular area.

Of the outer eyelids, the lower alone is movable in most birds, as in reptiles, and it frequently contains a rather large saucer-shaped cartilage, the _tarsus palpebralis_. The margins of the lids are sometimes furnished with eyelashes, e.g. in the ostrich and in the Amazon parrots, which are vestigial feathers without barbs. During the embryonic stage the lids are fused together, and either become separated shortly before the bird is hatched, as is the case with most Nidifugae, or else the blind condition prevails for some time, in the young Nidicolae. All birds have, like most reptiles, a well-developed third lid or "nictitating membrane," which moves from the inner canthus obliquely upwards and backwards over the cornea. The moving mechanism is a further and much higher development of that which prevails in reptiles, there being two muscles completely separate from each other. Both are supplied by the _abducens_ nerve, together with the _rectus externus_ muscle. One, the _quadratus_ or _bursalis_ muscle, arises from the hinder surface of the eyeball, and forms with its narrow margin, which is directed towards the optic nerve, a pulley for the long tendon of the _pyramidalis_ muscle. This arises from the nasal surface of the ball, and its tendon passes into the somewhat imperfectly transparent nictitating membrane. The quadrate muscle adjusts the motion, and prevents pressure upon the optic nerve; during the state of relaxation of both muscles the nictitans withdraws through its own elasticity.

See R. Leuckart in Graefe and Saemisch's _Handbuch d. Ophthalmologie_ (Leipzig, 1876, vol. i. chap. 7); H. Mueller, _Gesammelte Schriften_ (Otto Becker, Leipzig, 1872), and _Arch. f. Ophthalmol._ iii.; Ch. Rouget, "Recherches anatomiques et physiologiques sur les appareils erectiles," "Appareil de l'adaptation de l'oeil" ... _Compt. Rend._ (Paris, xlii., 1856, pp. 937-941); M. Schultze, art. "Retina," in Stricker's _Handbuch der Gewebelehre_, 1871, vol. ii.; J.R. Slonaker, "Comp. Study of the Area of Acute Vision in Vertebrates," _Journ. Morph._, 1897.

_Ear._--The outer opening of the ear is, with rare exceptions, concealed by feathers, which are often rather stiff, or modified into bristles. There is no other protection, but slight, imperfectly movable folds of skin arise from the outer rim. The largest ear-opening is met with in the owls, with correspondingly larger folds of skin, the function of which is less that of protection than, probably, the catching of sound. In many owls the right and left ears are asymmetrical, and this asymmetry affects the whole of the temporal region, all the bones which surround the outer and middle ear, notably the squamosal and the quadrate, so that the skull becomes lopsided, one ear being turned obliquely down, the other upwards. (For, detail see Collett, _Christiania Vidensk. Forhandl._, 1881, No. 3.)

The middle ear communicates with the mouth by the Eustachian tubes, which pass between the basisphenoid and basioccipital bones, and unite upon the ventral side of the sphenoid, a little behind its articulation with the pterygoids, where they open into the mouth cavity by a short membranous duct. The columellar apparatus, or auditory chain of ossicles (fig. 16), extending between the fenestra ovalis and the tympanic membrane or drum, consists of (1) the long and slender columella, a straight, ossified rod which fits with a disk into the fenestra ovalis; it is homologous with the stapes (_m.st._), although not stirrup-shaped; (2) the extracolumellar mass. This is chiefly cartilaginous and sends out three processes: the dorsal (_s. st._) is attached to the upper wall of the drum cavity; the outermost (_e. st._) is fastened on to the middle of the drum membrane; the third, ventral or infracolumellar process (_i. st._) is directed downwards and tapers out into a thin, partly cartilaginous, strand, which originally extended to the inner corner of the articular portion of the mandible, but on its long way comes to grief, being squeezed in between the pterygoid and quadrate. This long downward process being homologous with an almost exactly identical arrangement in the crocodile, and with the _processus folii_ of the mammalian malleus, it follows that the whole extracolumellar mass, that between stapes and drum, is equivalent to incus and malleus of the mammalia. There is, in birds, no _annulus tympanicus_. Birds possess an ear-muscle which at least acts as a _tensor tympani_; it arises near the occipital condyle, passes through a hole into the tympanic cavity, and its tendon is, in various ways, attached to the inside of the membrane and the neighbouring extracolumellar processes.

As regards the inner ear, the endolymphatic duct ends in a closed _saccus_, imbedded in the dura mater of the cranial cavity. The apex of the cochlea is turned towards, and almost reaches the anterior wall of the occipital condyle; at most it makes but half a twist or turn; it possesses both Reissner's membrane and the organ of Corti. Although the _scala tympani_ is so rudimentary, not reaching a higher level than in most of the reptiles, and remaining far below the mammalia, birds do not only hear extremely well, but they distinguish between and "understand" pitch, notes and melodies.

See G. Breschet, _Recherches anatomiques et physiologiques sur l'organe de l'audition chez les oiseaux_ (Paris, 1836), with Atlas; C. Hasse, various papers in _Zeitschr. f. wiss. Zool_. vol. xvii, and in _Anatomische Studien_, pts. ii. and iv. (Bresku, 1871); I. Ibsen, _Atlas anatomicus auris internae_ (Copenhagen, 1846); G. Retzius, _Das Gehororgan der Wirbelthiere_ (Stockholm, 1884), ii. pp. 139-198, pls. 15-20.

_Nose._--The olfactory organ is poorly developed, and it is still a question whether birds possess much power of smell; many are certainly devoid of it.

The olfactory perceptive membrane is restricted to the posterior innermost region of the nasal chamber, where it covers a slight bulging-out prominence on the nasal wall. This so-called third, upper or posterior conch is not a true conch, nor is that of the vestibulum; only the middle one forms a scroll, and this corresponds to the only one of reptiles and the lower of the mammals. The nasal cavity communicates with the mouth by the choanae or posterior nares, situated between the palatine process of the maxillary, the palatine and the vomer. The outer nares or nostrils are most variable in size and shape. In the Steganopodes they tend to become much reduced, e.g. in cormorants (_Phalacrocoracidae_), and especially in _Sula_, where the nasal slits become completely closed up, and the greater portion of the nasal cavity is also abolished, being restricted to the olfactory region with its unusually wide choanae. The nasal septum is often more or less incomplete, producing _nares peniae_, e.g. in the Cathartae, in the Anseres, gulls, rails and various other aquatic birds. The secretions of the mucous membrane of the nasal cavity, and a pair of naso-lacrymal glands (not to be confounded with the Harderian and the lacrymal glands), moisten and clean the chamber. The glands are variable in size and position; when very large, e.g. in plovers, they extend upon the forehead, causing deep impressions on the bones of the skull. Jacobson's organ has been lost by the birds, apparently without a trace in the embryonic fowl, but T.J. Parker has described vestiges of the corresponding cartilages in the _Apteryx_ (_Phil. Trans._, 1890).

See C. Gegenbaur, "Ueber die Nasenmuscheln der Voegel," _Jena Zeitschr_. vii., 1873, pp. 1-21.

5. _Vascular System._

The _heart_ lies in the middle line of the body, its long axis being parallel with that of the trunk. The whole ventral surface of the pericardium is exposed when the sternum is removed. The right and left halves are completely divided by septa, no mixture of the venous and arterial blood being possible, an advance upon reptilian conditions, even the highest.

The atria are comparatively small, the walls being thin, especially those of the right, which possesses numerous muscular ridges projecting into the cavity presenting a honeycombed appearance. The interauricular septum is mostly entirely membranous; in the middle it is thinner, rather transparent, but there is no depression or _fossa ovalis_. The whole sinus venosus has become part of the right atrium. It receives the three great venous trunks of the body, namely the _vena cava superior dextra_, the _vena cava superior sinistra_ more dorsally, and the _vena cava inferior_ more to the right and below; the opening of the last is guarded by two prominent valves in place of the mammalian _valvula Eustachii_. The right ventricle occupies the ventral portion of the heart. The communication with the atrium is guarded by a _valvula cardiaca dextra_, which only in function represents the mammalian tricuspid; it consists of an oblique reduplication of the muscular fibres together with the endocardiac lining of the right ventricle, while the opposite wall is convex and forms neither a velum nor papillary muscles, nor _chordae tendineae_. The right anterior corner of the right ventricle passes into the short stem, guarded by three semi-lunar valves, which divides into the two pulmonary arteries. There are likewise two pulmonary veins, entering the left atrium by one orifice. Two or three membranous flaps, held by numerous _chordae tendineae_, form a true mitral valve, and allow the blood to pass through the left _ostium atrioventriculare_. The blood leaves the heart past three semi-lunar valves, by the _right_ aorta, this being alone functional, a feature characteristic of, and peculiar to, birds. Remnants of the left aortic arch persist sometimes in the shape of a ligamentous strand. The aortic trunk is very short, sends off the coronary arteries and then the left _aorta brachiocephalica_, while the rest divides into the right brachiocephalic and the _aorta descendens_. Each brachiocephalic soon sends off its subclavian, while in the normal or more usual cases the rest proceeds as the carotid trunk, inclusive of the vertebral artery. But the carotids show several interesting modifications which have been examined chiefly by C.L. Nitzsch and by A.H. Garrod. (1) The right and left carotids converge towards the middle and extend up the neck, imbedded in a furrow along the ventral surface of the cervical vertebrae. This is the usual arrangement. (2) The two carotids are fused into one _carotis conjuncta_, imbedded in a special median osseous semicanal of the vertebrae; e.g. herons, flamingos, and some parrots. (3) There is one _carotis conjuncta_, but the basal portion of its original right component is obliterated, leaving a so-called _c. primaria sinistra_, an unfortunate name. Such _Aves laevocarotidinae_ of Garrod are common, e.g. all the Passeriformes. (4) The reverse of the third modification, producing a _c. primaria dextra_ in the bustard _Eupodotis_. In other likewise very rare cases a left, or a left and right, superficial carotids are developed and take the place of the then vanished deep or primary carotids.

_Venous System._--The bird's liver receives nearly all the blood from the stomach, gut, pancreas and spleen, as well as from the left liver itself, into the right hepatic lobe, by a right and left portal vein. The _venae hepaticae magnae_ join the _vena cava posterior_ and thereby form with it the _vena cava inferior_. The left _hepatica magna_ receives also the umbilical vein, which persists on the visceral surface of the abdominal wall, often anastomosing with the epigastric veins. A likewise unpaired vena _coccygeo-mesenterica_ is usually present. There is no renal portal system, excepting unimportant vestiges of such a system in the head kidneys.

_Lymphatic System._--The white blood-corpuscles are produced in the follicles at the base of the intestinal villi. The lymph vessels of the tail and hinder parts of the body enter the hypogastric veins; and at the point of junction, on either side, lies a small lymph heart, which often persists until maturity. The red blood-corpuscles are invariably oval disks, with a central nucleus which causes a slight swelling; hence they are oval and biconvex.

See A.H. Garrod, "On the Carotid Arteries of Birds," _Proc. Zool. Soc._, 1873, pp. 457-472; E.A. Lauth, "Memoire sur les vaisseaux lymphatiques des oiseaux," _Ann, Sci. nat._ (iii. 1824), p. 381; J.J. Mackay, "The Development of the Branchial Arterial Arches in Birds, with special reference to the Origin of the Subclavians and Carotids," _Phil. Trans._ 179 B (1888), pp. 111-141; L.A. Neugebauer, "Systema venosum avium," _Nov. Act. Leopold. Carol._ xxi., 1844, pp. 517-698, 15 pls.; R. Gasch, "Beitraege zur vergl. Anatomic des Herzens der Voegel und Reptilien," _Arch. f. Naturgesch._, 1888.

6. _Respiratory System._

The _lungs_ are small and occupy only the dorsal portion of the thoracic cavity. There is only one right and one left lobe, each traversed through its whole length by a _mesobronchium_, whence arise about ten secondary bronchia; these send off radially arranged _parabronchia_, which end blindly near the surface. The walls of these tertiary tubes send out, in all directions, _canaliculi aeriferi_ which, ending in slight swellings, recall the mammalian _aveoli_.

Highly specialized air-sacs are characteristic of all birds. They are very thin-walled membranes, very poor in blood-vessels, formed by the bulged-out pleural or peritoneal covering of the lungs, through the parabronchial tubes of which they are filled with air. Their function is not quite clear. The usual suggestion, that the warm air contained within them assists the bird in flight, balloon-like, is absurd. They assist in the extremely rapid and vigorous ventilation of the lungs, the latter being capable of but very limited expansion and contraction in birds. Exchange of gas through the walls of the air-sacs, almost devoid of blood-vessels, can at best be much restricted.

There are five pairs of larger sacs belonging to the pulmonary system:--(1) prebronchial or cervical, extending sometimes far up the neck, even into the cranial cavities; the throat-bags of the prairie fowls (_Cupidonia_ and _Pedioecetes_) are a further development; (2) subbronchial or interclavicular; (3 and 4) anterior and posterior thoracic or intermediate; (5) abdominal sacs. Most of these extend through narrow apertures--_foramina pneumatica_--into the hollow bones, sometimes, e.g. in hornbills and screamers, into every part of the skeleton, or, in the shape of innumerable pneumatic cells, even beneath the skin. There is also a naso-pharyngeal or tympanic system of air-sacs, restricted to the head (cf. the _siphonium_ described in connexion with the mandible), but filling also such curious organs as the frontal excrescence of _Chasmorhynchus_, the Brazilian bell-bird, the throat-bag of the adjutant stork, and the gular pouch of the bustard.

The _trachea_ or windpipe is strengthened by numerous cartilaginous, often osseous, complete rings, but in the emeu several of these rings are incomplete in the medioventral line, and permit the inner lining of the trachea to bulge out into a large neck-pouch, which is used by both sexes as a resounding bag. In humming-birds and petrels the trachea is partly divided by a vertical, longitudinal, cartilaginous septum. In some of those birds which have a peculiarly harsh or trumpeting voice, the trachea is lengthened, forming loops which lie subcutaneously (capercally, curassow), or it enters and dilates the symphysis of the furcula (crested guineafowl); or, e.g. in the cranes and in the hooper swan, even the whole crest of the sternum becomes invaded by the much elongated, manifolded trachea.

The _syrinx_ or lower larynx is the most interesting and absolutely avine modification, although absent as a voice-producing organ (probably due to retrogression) in most Ratitae, storks, turkey buzzards (_Cathartes_) and Steganopodes. The syrinx is a modification of the lower part of the trachea and of the adjoining bronchi. Essential are vibrating membranes between the cartilaginous framework, and next, special muscles for regulating the tension. The majority of birds possess a pair of internal tympaniform membranes forming the inner or median walls of the bronchi, which are there furnished with semi-rings only. External tympaniform membranes exist, with great variations, between the specialized one or two last tracheal and some of the first bronchial rings.

According to the position of the chief sound-producing membranes, three types of syrinx are distinguishable:--(1) Tracheo-bronchial, by far the commonest form, of which the two others are to a certain extent modifications. The essential feature is that the proximal end of the inner membranes is attached to the last pair of tracheal rings; outer tympaniform membranes exist generally between the 2nd, 3rd and 4th bronchial semi-rings. This type attains its highest development in the Oscines, but it occurs also in many other orders. (2) Syrinx _bronchialis_. The outer membranes are spread out between two or more successive bronchial semi-rings, a distance from the trachea which is, in typical cases, devoid of sounding membranes; some Cuculi, Caprimulgi, and some owls. (3) Syrinx _trachealis_. The lower portion of the trachea consists of thin membranes, about half a dozen of the rings being very thin or deficient. Inner and outer membranes may exist on the bronchi. The _Tracheophonae_ among the Passeriformes, the possessors of this specialized although low type of syrinx, form a tolerably well-marked group, entirely neotropical. But indications of such a syrinx occur also in _Pittidae_, pigeons and gallinaceous birds (_Gallidae_), the last cases being clearly analogous.

Whilst the type of syrinx affords no help in classification, it is very different with its muscles. These--as indicated by their supply from a branch of the hypoglossal nerve, which descends on either side of the trachea--are, so to speak, a detached, now mostly independent colony of glosso-pharyngeal muscles. Omitting the paired tracheo-clavicular muscles, we restrict ourselves to the syringeal proper, those which extend between tracheal and bronchial rings. Their numbers vary from one pair to seven, and they are inserted either upon the middle portion of the bronchial semi-rings (_Mesomyodi_), or upon the ends of these semi-rings where these pass into the inner tympaniform membrane (_Acromyodi_). The former is morphologically the more primitive condition, and is found in the overwhelming majority of birds, including many Passeriformes. The acromyodian type is restricted almost entirely to the Oscines. Further, according to these muscles being inserted only upon the dorsal, or only upon the ventral, or on both ends of the semi-rings, we distinguish between _an_-, _kat_- and _diacromyodi_. But the distinction between such _Acromyodi_ and the _Mesomyodi_ is not always safe. For instance, the _Tyranninae_ are anacromyod, while the closely allied Pipras and Cotingas are katacromyod; both these modifications can be shown to have been derived but recently from the weak meso- and oligomyodian condition which prevails in the majority of the so-called _Oligomyodi_. On the other hand, the diacromyodian type can have been developed only from a strong muscular basis which could split into a dorsal and a ventral mass; moreover, no Passeres are known to be intermediate between those that are diacromyodian and those that are not.

Attempts to derive the anacromyodian and the katacromyodian from the diacromyodian condition are easy on paper, but quite hopeless when hampered by the knowledge of anatomical facts and how to use them. There remains but one logical way, namely, to distinguish as follows:--(1) _Passeres anisomyodi_, in which the syrinx muscles are unequally inserted, either on the middle or on one end of the semi-rings, either dorsal or ventral. This type comprises the Clamatores. (2) _Passeres diacromyodi_, in which some of the syrinx muscles are attached to the dorsal, and some to the ventral ends, those ends being, so to say, equally treated. This type comprises the Oscines. Both types represent rather two divergent lines than successive stages, although that of the Clamatores remains at a lower level, possessing at the utmost three pairs of muscles, whilst these range in the Oscines from rarely two or three to five or seven.

This way of using the characters of the syrinx for the classification of the Passeriformes seems simple, but it took a long time to accomplish. Joh. Mueller introduced the terms _Polymyodi_ and _Tracheaphones_, Huxley that of _Oligomyodi_; Mueller himself had, moreover, pointed out the more important characters of the mode of insertion, but it was Garrod who invented the corresponding terms of _Acro_-and _Mesomyodi_ (= _Tracheophones_ + _Oligomyodi_). (For further historical detail, see ORNITHOLOGY). After W.A. Forbes had investigated such important genera as _Philepitta_ and _Xenicus_, P.L. Sclater, A. Newton and R.B. Sharpe divided the Passeres respectively into _Oscines, Oligomyodae, Tracheophonae_ and _Pseudoscines_ (= _Suboscines_); _Oligomyodae, Tracheophonae_ and _Acromyodae; Oscines, Oligomyodae, Tracheophonae_ and _Atrichiidae_. Ignoring the fact that some _Oligomyodae_ are meso- and others acromyodian, they tried to combine two irreconcilable principles, namely, mere numbers against quality.

BIBLIOGRAPHY.--M. Baer, "Beitr. z. Kenntniss d. Atemwerkzeuge bei den Voegeln," _Zeitschr. wiss. Zool_. lxi. 1896, pp. 420-498; Campana, _Physiologie de la respiration chez les oiseaux. Anatomie de l'appareil pneumatique_ ... (Paris, 1875); A.H. Garrod, "Major Divisions of Passerine Birds (syrinx, &c.)," _P.Z.S._, 1876, pp. 506-519; and "On the Conformation of the Thoracic Extremity of the Trachea in the Class _Aves_," _P.Z.S._, 1879, pp. 357-380; J. Mueller, _Stimmorgane der Passerinen_, Mueller's Arch. (1847); and _Abh. Akad. Wiss_. (Berlin, 1845-1847), translation by F.J. Bell, Oxford, 1878; H. Strasser, "Luftsacke der Voegel," _Morph. Jahrb_. iii., 1877, pp. 179-227; C. Wunderlich, "Unterer Kehlkopf der Voegel," _Nov. Act. Leop. Carol_., 1884; Ph. C. Sappey, _Recherches sur l'appareil respiratoire des oiseaux_ (Paris, 1847); W.A. Forbes, "Contributions to the Anatomy of Passerine Birds (syrinx)," _P.Z.S._, 1880, pp. 380-386, 387-391; 1881, pp. 435-737; 1882, pp. 544-546, 569-571; W. Yarrell, "Observations on the tracheae of Birds," _Trans. Linn. Soc_., 1827, pp. 378-391.

7. _Digestive System_.

For a general account of the digestive organs, see ALIMENTARY CANAL. Here only a few peculiar features may be mentioned.

The young pigeons are fed by both parents with a peculiar stuff, the product of the strongly proliferating epithelial cells of the crop, which cells undergo a cheese-like fatty degeneration, and mixed with mucus, perhaps also with the proventricular juice, make up a milk-like fluid. Should the young die or be removed during this period, the parents are liable to die, suffering severely from the turgid congestion of the hypertrophied walls of the crop.

The male of the hornbills, _Bucerotinae_, feeds his mate, which is imprisoned, or walled-up in a hollow tree, during the whole time of incubation, by regorging his food. This bolus is surrounded, as by a bag, by the cast-up lining of the gizzard. Since this process is repeated for many days the habitual reaction of the stomach well-nigh exhausts the male. A graphic account of this is given in Livingstone's travels.

The hoactzin, _Opisthocomus_, feeds to a great extent upon the leaves of the aroid _Montrichardia_ or _Caladium arborescens_. The crop is modified into a large and very rugose triturating apparatus, while the gizzard, thereby relieved of its function, is reduced to the utmost. The large and heavy crop has caused a unique modification of the sternal apparatus. The keel is pushed back to the distal third of the sternum, whilst the original anterior margin of the keel is correspondingly elongated, and the furcula fused with the rostral portion.

In the ostrich, _Struthio_, the craze of overloading the stomach with pebbles which, when triturated into sand, are not voided, has brought about a dislocation, so that the enormously widened and stretched space between proventriculus and gizzard forms a bag, directed downwards, whilst the gizzard itself with part of the duodenum is rotated round its axis to more than 100 deg.. A similar rotation and dislocation occurs in various petrels, in correlation with the indigestible sepia-bills, &c., which these birds swallow in great quantities. In _Plotus_, the snakebird, the pyloric chamber of the stomach is beset with a mass of hair-like stiff filaments which permit nothing but fluid to pass into the duodenum. The gizzard of various birds which are addicted to eating hairy caterpillars, e.g. _Cuculus canorus_ and trogons, is often lined with the broken-off hairs of these caterpillars, which, penetrating the cuticle, assume a regular spiral arrangement, due to the rotatory motion of the muscles of the gizzard.

8. _Cloaca and Genital Organs._

The cloaca is divided by transverse circular folds, which project from its inner walls, into three successive chambers. The innermost, the coprodaeum, is an oval dilatation of the end of the rectum, and attains its greatest size in those birds whose faeces are very fluid; it serves entirely as the temporary receptacle of the faeces and the urine. The next chamber, the urodaeum, is small, and receives in its dorso-lateral wall the ureters and the genital ducts; above and below this chamber is closed by circular folds, the lower of which, towards the ventral side, passes into the coating of the copulatory organ when such is present. The urodaeum serves only as a passage, the urine being mixed with the faeces in the chamber above. The third or outermost chamber, the proctodaeum, is closed externally by the sphincter ani; the orifice is quite circular. It lodges the copulatory organ, and on its dorsal wall lies the _bursa Fabricii_, an organ peculiar to birds. It is most developed in the young of both sexes, is of unknown function, and becomes more or less obliterated in the adult. Only in the ostrich it remains throughout life, being specialized into a large receptacle for the urine, an absolutely unique arrangement. A true urinary bladder, i.e. a ventral dilatation of the urodaeum, is absent in all birds. It is significant that the whole type of their cloaca much resembles that of the Crocodilia and Chelonia, in opposition to that of the Lacertilia.

The penis, and its much reduced vestige of the female, is developed from the ventral wall of the proctodaeum. It occurs in two different forms. In the Ratitae, except _Rhea_, it consists mainly of a right and left united half (_corpora fibrosa_), with a deep longitudinal furrow on the dorsal side, and much resembles the same organ in crocodiles and tortoises. It is protruded and retracted by special muscles which are partly attached to the ventral, distal end of the ilium. Another type exists in _Rhea_ and in the _Anseriformes_, greatly specialized by being spirally twisted and partly reversible like the finger of a glove. This is mainly due to the greater development of an unpaired, median portion, analogous to the mammalian _corpus spongiosum_, which is much less prominent in the Ratitae; the muscles of this type are derived solely from the anal sphincter. In other Carinatae, e.g. tinamous and storks, the penis is very much smaller and simpler, with every appearance of a degenerated organ. In the great majority of birds it has disappeared completely and the primitive way of everting the cloaca is resorted to.

Both right and left testes are functional. They become greatly enlarged in the breeding season; in the sparrow, for instance, from the size of a mustard seed to that of a small cherry. The vas deferens descends with many undulations down the lateral side of the ureter of the same side, and opens upon a small papilla into the urodaeum. Extraordinary increase in length during the breeding season causes the vasa deferentia in some of the African weaver-birds to protrude, or to bulge out the cloacal walls beyond the vent. The spermatozoa exhibit many differences in shape, size and proportions, in the various groups of birds. They have been studied minutely by E. Ballowitz.

Only the left ovary becomes functional, with rare individual exceptions. Both present the appearance of diminutive clusters of grapes, at the anterior end of the kidneys, close to the suprarenal bodies, separated from each other by the descending aorta and by the vena cava where this is formed by the right and left _vena iliaca communis_. During the breeding season many more eggs are developed than reach maturity, amounting in most birds to several dozens. Those germs which do not ripen during the season undergo a process of resorption, and in the winter the whole ovary dwindles to often a diminutive size. In young birds both oviducts are almost equal in size, but the right soon degenerates into an insignificant strand. During every laying season the left duct increases enormously by new formation of its component fibres. For instance, in the fowl its volume increases about fifty-fold, growing from some 6 in. in length and scarcely one line in width to more than 2 ft. in length and 1/2 in. in thickness. The upper, wide opening of the duct is attached by elastic, peritoneal lamellae to the hinder margin of the left lung; the middle portion of the duct is glandular and thick-walled, for the deposition of the albumen; it is connected by a short, constricted "isthmus" (where the shell-membrane is formed) with a dilated "uterus" in which the egg receives its calcareous shell and eventual pigmentation.

BIBLIOGRAPHY.--A. v. Brunn, _Rueckbildung nicht ausgestossener Eierstockseier, Henle Festschrift_ (Bonn, 1882); E. Ballowitz, "Die Spermatozoen der Voegel," _Arch. Mikr. Anat._ xxxii., 1888, pls. 14-18; M. Sacchi, "Contribuzione all' istiologia del ovidotto dei saurop-sidi," _Att. Soc. Ital._, Milano, vol. xxx.; W.A. Forbes, "On the Bursa Fabricii in Birds," _P.Z.S._, 1877, pp. 304-318; H. Gadow, "Remarks on the Cloaca and on the Copulatory Organs of the Amniota." _Phil. Trans._, 1887, pp. 5-37, pls. 2-5; Martin Saint Ange, "Etude de l'appareil reproducteur dans les cinq classes d'animaux vertebres," _Mem. Ac. Soc._, Paris, xiv., 1856; E. Retterer, "Contribution a l'etude du cloaque et de la bourse de Fabricius," _Robin's Journ. de l'anat. et physiol._, 1885, pp. 369-454, pls. 17-19.

B. FOSSIL BIRDS

Much had naturally been expected from the study of fossil birds, but, so far as the making of classifications is concerned, they have proved rather a source of perplexities. So long as the characters of new fossils are only of specific and generic value, it is mostly possible to assign the birds to their proper place, but when these characters indicate new families or orders, for instance Hesperornithes, Ichthyornithes, Palaelodi, their owners are put outside the more tersely constructed classifications applicable to modern birds. It is no exaggeration to say that the genus, often even the species, can be determined from almost any recent bone, but in the case of Miocene, and still more, of Eocene fossils, we have often to deal with strange families, which either represent an extinct side branch, or which connect several recent groups with each other. Our artificially-established classifications collapse whilst we gain further insight into the mutual affinities of the existing groups. Of course this must be so if evolution is true. But it also follows that, if every extinct and recent bird were known, neither species, nor genera, nor families, nor orders could be defined. We should be able to construct the pedigree of every group, in other words, the gigantic natural system, but there would be no classification. Much light has also been thrown by fossil birds upon the study of geographical distribution. The key to the distribution of recent groups lies in that of the extinct forms. Not only have many absolutely new families been discovered, but many kinds of modern birds are now known to have existed also in countries which they are now extinct. There were, for instance, trogons, secretary-birds, parrots, and other now Ethiopian forms in Miocene France. Ostriches, undistinguishable from _Struthio_, have been found in Samos and in the Sivalik Hills.

The proper study of fossil birds may be said to have begun with A. Milne-Edwards, whose magnificent _Oiseaux fossiles de la France_ was published from 1867 to 1871. This work deals chiefly with mid-Tertiary forms. A new impetus was given by O.C. Marsh, who, after 1870, discovered a great number of bird remains in the Cretaceous strata of North America. The most important result is the proof that, until the end of the Cretaceous epoch, most, if not all, birds were still possessed of teeth (see ODONTORNITHES).

The oldest known bird is the _Archaeopteryx_ (q.v.), of the upper Oolite in Bavaria. The imprints in the enormously older new red sandstone or Lower Trias of Connecticut, and originally named _Ornithichnites_, belong to Dinosaurian Reptiles.

A wide gap separates _Archaeopteryx_ from the next order of fossil birds of the Cretaceous epoch, and, since freshwater deposits of that age are rare, bird remains are uncommon. Many bones formerly referred to birds have since proved to belong to Pterodactyls, e.g. _Cimoliornis_ from the English Chalk. But in 1858 were discerned in the Upper Greensand of Cambridgeshire remains which are now known as _Enaliornis_. W. Dames has described bones from the Chalk of southern Sweden under the name of _Scaniornis_, probably allied to _Palaelodus_. From the Cretaceous rocks of North America a large number of birds have been described by O.C. Marsh. Of these the most interesting are _Ichthyornis_ (= _Graculavus_) and _Hesperornis_, from the Cretaceous shales of Kansas. They were placed by Marsh in a distinct subclass of birds, _Odontornithes_ (q.v.). Probably all birds of Cretaceous age were still possessed of teeth. _Baptornis_, another of Marsh's genera, seems to be allied to _Enaliornis_, _Palaeotringa_ and _Talmatornis_, were by him referred to Limicoline and Passerine birds. _Laornis_ from the Cretaceous marls of New Jersey was as large as a swan.

The lower Eocene has furnished a greater number of bird bones. Some of the largest are those of _Gastornis_, with three species from France, Belgium and England. Much difference of opinion obtains as to the affinities of these birds, which were far larger than an ostrich; they were undoubtedly incapable of flight and there are indications of teeth in the upper jaw. Provisionally this genus has been grouped with the Ratitae, which at any rate are a heterogenous assembly. Sir R. Owen's _Dasornis_, of the London Clay, known from an imperfect cranium, and E.D. Cope's _Diatryma_ of New Mexico, based upon a gigantic metatarsus, may also belong there. The London Clay of South England has likewise supplied some long upper arm bones, _Argillornis_. The most remarkable specimen is a skull, _Odontopteryx toliapicus_ (figs. 17, 18); the edges of the jaws were serrated like those of certain tortoises. The character of this skull and the compound rhamphotheca (known by the imprints left upon the jaws) indicate affinities with the Steganopodes. Remnants of a heron-like bird, _Proherodius_, of a gull-like creature, _Halcyornis_, a raptorial _Lithornis_; and a supposed Passerine from Glarus in Switzerland, called _Protornis = Osteornis_, complete the list.

The upper Eocene has yielded many birds, most of which are at least close forerunners of recent genera, the differentiation into the leading orders and families being already well marked, e.g. Gallinaceous birds, stork- and crane-like waders, rails, birds of prey, cormorants, &c. Especially numerous bones have been found in the Paris basin, chiefly described by G. Cuvier, F.L.P. Gervais, E. Blanchard, and above all by A. Milne-Edwards, and in the equivalent beds of Hampshire. Others have been discovered in Wyoming; a giant penguin, _Palaecudyptes_, is known from New Zealand, and _Palaeospheniscus_ from Patagonia. The Miocene has yielded by far the greatest number of bird-bones, including even eggs and imprints of feathers. For instance, from the lower Miocene beds of Allier and Puy-de-Dome Milne-Edwards has described about 50 species. Of these _Palaelodus_ was an ancestral flamingo, but with shorter legs; _Limnatornis_ is referred to the hoopoes. The existing genera include _Anas, Aquila, Bubo, Columba, Cypselus, Lanius, Picus, Phalacrocorax, Sula_, &c. Very interesting is the fact that _Serpentarius, Psittacus_ and _Trogon_ are amongst this list of birds, which are now restricted to the tropics. A similarly mixed avifauna has been found in the mid-Miocene beds of various other parts of France, Germany and Italy. In Colorado and New Mexico Marsh has detected bones of _Meleagris, Puffinus, Sula_ and _Uria_, all existing genera; but the first is especially suggestive, since it is one of the most characteristic forms of the New World.

Here may be interpolated a short account of the very peculiar avifauna found in the Tertiary strata of Santa Cruz in Patagonia. Instead of the age of lower Eocene, as had been stated originally, these beds are not older than mid-Miocene, and not a few of the bones are of a much younger, even latest Tertiary date. Discovered, and partly described, by F. Ameghino, the bones have been sumptuously monographed by F.P. Moreno and A. Mercerat, who proposed for them the name of _Stereornithes_, a new order of birds, mostly gigantic in size, and said to combine the characters of Anseres, Herodiones and Accipitres. But the whole mass of bones is in hopeless disorder, apparently without any record of association. At any rate, the "_Stereornithes_," accepted as such in Bronn's _Thierreich_, and in Newton's _Dictionary of Birds_, had to be dissolved as an unnatural, haphazard assembly. Many of these birds, to judge from the enormous size of their hind-limbs, were undoubtedly flightless, e.g. _Brontornis_, and remind us of the Eocene _Gastornis_ of Europe. _Phororhacos_, the most extraordinary of all, belongs to the Gruiformes, perhaps also _Pelecyornis_ and _Liornis_. On the other hand, the late Tertiary _Dryornis_ is a member of the Cathartae or American vultures, and _Mesembriornis_, likewise of late Tertiary date, is a close forerunner of the recent genus _Rhea_.

Pliocene remains are less numerous than those of the Miocene. From Pikermi in Greece is known a _Gallus_, a _Phasianus_ and a large _Grus_. From Samos a large stork, _Amphipelargus_, and a typical _Struthio_; from the Sivalik Hills on the southern flanks of the Himalayas also an ostrich, and another Ratite with three toes, _Hypselornis_, as well as _Leptoptilus, Pelecanus_ and _Phalacrocorax_. The fossil egg of a struthious bird, _Struthiolithus_, has been found near Cherson, south Russia, and in north China. The Suffolk Crag has yielded the unmistakable bones of an albatross, _Diomedea_.

Most Pleistocene birds are generically, even specifically, identical with recent forms; some, however, have become extinct, or they have become exterminated by man. A great number of birds' bones have been found in caves, and among them some bearing marks of human workmanship. In France we have a large and extinct crane, _Grus primigenia_, but more interesting are the numerous relics of two species, the concomitants even now of the reindeer, which were abundant in that country at the period when this beast flourished there, and have followed it in its northward retreat. These are the snowy owl, _Nyctea scandiaca_, and the willow-grouse, _Lagopus albus_. A gigantic swan, _Cygnus falconeri_, is known from the Zebug cavern in Malta. From caves of Minas Geraes in Brazil, O. Winge has determined at least 126 species, of which nearly all still survive in the country. Kitchen-middens of England, Ireland and Denmark reveal the existence of the capercally, _Tetrao urogallus_, and of the great auk or gare-fowl, _Alca impennis_; both species long since vanished from those countries. In the fens of East Anglia have been found two humeri, one of them immature, of a true _Pelecanus_, a bird now no longer inhabiting middle Europe.

Until a very recent epoch there flourished in Madagascar huge birds referable to the Ratitae, e.g. _Aepyornis maximus_, which laid enormous eggs, and not unnaturally recalls the mythical "roc" that figures so largely in Arabian tales. New Zealand has also yielded many flightless birds, notably the numerous species and genera of _Dinornithidae_, some of which survived into the 19th century (see MOA); _Pseudapteryx_ allied to the _Kiwi; Cnemiornis_, a big, flightless goose; _Aptornis_ and _Notornis_, flightless rails; and _Harpagornis_, a truly gigantic bird of prey with tremendous wings and talons.

It is, of course, quite impossible, in a survey of extinct birds, to divide them into those which are _bona fide_ fossil, sub-fossil, recently extirpated and partially exterminated. Nor is it possible, except in a few cases, to decide whether they have come to an end through the agency of man or through so-called natural causes. Like other creatures birds have come, some to flourish and stay, others to die out.

Mauritius is famous for the dodo, killed off by man; there was also a curiously crested parrot, _Lophopsittacus_ (fig. 19). In the Mare aux Songes have been found the bones of another parrot, of ducks, pigeons, rails, herons, geese and of a dwarf darter, _Plotus nanus_, all sub-fossil, now extinct. Very interesting is _Aphanapteryx_ (fig. 20), a long-billed, flightless rail, practically the same as _Erythromachus_ of Rodriguez and _Diaphorapteryx_ of Chatham Island. Reunion possessed the peculiar starling, _Fregilupus_. Rodriguez was inhabited by _Pezophaps_, the solitaire, _Necropsittacus_ and _Palaeornis exsul_, which is now probably extinct. The Antilles tell a similar tale. The great auk, once common on the British coasts, those of Denmark, the east coast of North America, then restricted to those of Newfoundland, Greenland and Iceland, has been killed by man, and the same fate has overtaken the Labrador duck, the Phillip Island parrot, _Nestor productus_, and the large cormorant of Bering Island, _Phalacrocorax perspicillatus_; and how long will the flightless cormorant, _Ph. harrisi_ of the Galapagos, survive its quite recent discovery?

AUTHORITIES.--A. Milne-Edwards, _Recherches anatomiques et paleontologiques pour servir a l'histoire des oiseaux fossiles de la France_ (Paris, 1867-1868); F.P. Moreno and A. Mercerat, _Catalogo de los Pajaros fosiles de la Republica Argentina. Anales Mus. La Plata_, 1891, 21 pls.; O.C. Marsh, _Odontornithes: A monograph of the Extinct Toothed Birds of North America_ (New Haven, Conn., 1880); R. Lydekker, article "Fossil Birds," in A. Newton's _Dictionary of Birds_ (London, 1893); Cat. Foss. Birds, Brit. Museum, 1891; K. v. Zittel, _Handbuch der Palaontologie_, i. 3 (1887-1890); C.W. Andrews, "On the Extinct Birds of Patagonia," _Tr. Zool. Soc_. xv., 1899, pp. 55-86, pls. 14-17.

C. GEOGRAPHICAL DISTRIBUTION

The study of the extinct organisms of any country leads to a proper appreciation of its existing flora and fauna; while, on the other hand, a due consideration of the plants and animals which may predominate within its bounds cannot fail to throw more or less light on the changes it has in the course of ages undergone. That is to say, the distribution of forms in time is a subject so much connected with the distribution of forms in space, that the one can hardly be separated from the other. Granting this is a general truth, it must yet be acknowledged as a special fact, that in fossil birds we have as yet but scanty means of arriving at any precise results which will justify bold generalization in the matter of avine distribution. Remains of extinct birds are, compared with those of other classes of vertebrates, exceedingly scarce, and these have been found in very few, widely separated countries. The great problems involved in the study of geographical distribution must therefore be based mainly upon the other classes, both vertebrate and invertebrate, which, moreover, enjoy less great facilities of locomotion than the birds.

Yet it so happens that the great zoogeographical regions of the world, now more or less generally accepted, have been based upon the distribution of birds. The whole subject was properly introduced by Treviranus,[1] who in his large philosophical work devotes considerable space to the "geographical distribution of animals." Next we have to mention F. Tiedemann,[2] the Heidelberg anatomist, who has been generally ignored, although he surpassed many a recent zoogeographer by the wide view he took of the problem; in fact he was the first to connect distribution with environmental or bionomic factors; e.g. the remark on p. 481 of his work that "the countries of the East Indian flora have no kinds of birds in common with America which are vegetable feeders." L.K. Schmarda[3] divided the land into twenty-one realms, characterizing these mainly by their birds. P.L. Sclater[4] was the first to divide the world into a few great "regions," the Palaearctic, Ethiopian, Indian and Australian forming one group, the "Old World" (_Palaeogaea_); and the Nearctic and Neotropical forming a second, the New World (_Neogaea_). Birds being of all animals most particularly adapted for extended and rapid locomotion, it became necessary for him to eliminate from his consideration those groups, be they small or large, which are of more or less universal occurrence, and to ground his results on what was at that time commonly known as the order Insessores or Passeres, comprehending the orders now differentiated as Passeriformes, Coraciiformes and Cuculiformes, in other words the mass of arboreal birds. His six main divisions--practically adopted by A.R. Wallace[5] in his epoch-making work--are excellent, taken separately. They express the main complexes of land with their dependencies in well-chosen terms; for instance the "Neotropical region" stands short for South and Central America with the Antilles.

But these six divisions of Sclater and Wallace are not all equivalent, only some are of primary importance; they require co- and sub-ordination. This most important advance was made by T.H. Huxley.[6] Some of the "regions" have now to be called subregions, e.g. the Nearctic and the Palaearctic. The reduction of the Oriental to a subregion, with consequent "provincial" rank of its main subdivisions, will probably be objected to, but these are matters of taste and prejudice. Above all it should be borne in mind that nearly all the last subdivisions or provinces are of very little real value and most of them are inapplicable to other classes of animals.

Besides some occasional references in the text, only a few more of the general works dealing with the distribution of birds can here be mentioned. Especial attention has to be drawn to the article "Geographical Distribution," in Newton's _Dictionary of Birds_. See also A. Heilprin, _The Geographical and Zoological Distribution of Animals_ (New York, 1887); W. Marshall and A. Reichenow, two maps with much detail, although badly arranged, in Berghaus' _Physikalischer Atlas_, pt. vi. (_Atlas d. Thierverbreitung_), (Gotha, 1887); A. Reichenow, "Die Begrenzung zoogeographischer Regionen vom ornithologischen Standpunkte," _Zoolog. Jahrb._ iii., 1888, pp. 671-704, pl. xxvi.; E.L. Trouessart, _La Geographie zoologique_. (Paris, 1890).

The scheme adopted in the following account stands as follows:--

(A) AUSTROGAEA or I. Australian Region: New Zealand subregion. Australian " Papuan "

(B) NEOGAEA or II. Neotropical Region Antillean subregion Columbian " Patagonian "

(C) ARCTOGAEA III. Holarctic Region Nearctic Subregion Palaearctic "

IV. Palaeotropical Region Ethiopian Subregion Oriental "

In the following account the characterization of the various regions and subregions has to a very great extent been adopted from Newton's article in his _Dictionary of Birds_, and from the chapter on distribution in the article on "Birds" in the _Encyclopaedia Britannica_, 9th edition. This applies especially ~~ to those instances in which the members of families, genera and species are mentioned. The families are those which are enumerated in Garow's classification. The numbers of genera and species of birds are, of course, a matter of personal inclination. If we take a moderate computation the number of recent species may be taken at 10,000-11,000.[7] Dr R.B. Sharpe increases their number to about 15,000 in the _New Hand-List of Birds_, published by the British Museum. In the first two volumes fossil birds, occasionally based upon a fragmentary bone only, are also included.

(A) AUSTROGAEA, the Australian region in the wider sense, with the Papuan, Australian and New Zealand subregions, including also Polynesia. We may here quote Newton (_Encyclopaedia Britannica_, 9th ed., "Birds," p. 738) on the remarkable differences between this region and the rest of the Old World:--"The prevalent zoological features of any Region are of two kinds--negative and positive. It is therefore just as much the business of the zoogeographer, who wishes to arrive at the truth, to ascertain what groups of animals are wanting in any particular locality (altogether independently of its extent) as to determine those which are forthcoming there. Of course, in the former case it would be absurd to regard as a physical feature of any great value the absence from a district of groups which do not occur except in its immediate neighbourhood; but when we find that certain groups, though abounding in some part of the vicinity, either suddenly cease from appearing or appear only in very reduced numbers, and occasionally in abnormal forms, the fact obviously has an important bearing. Now, mere geographical considerations, taken from the situation and configuration of the islands of the so-called Indian or Malay Archipelago, would indicate that they extended in an unbroken series from the shores of the Strait of Malacca to the southern coast of New Guinea, which confronts that of north Australia in Torres Strait, or even farther to the eastward. Indeed, the very name Australasia, often applied to this part of the world, would induce the belief that all the countless islands, be they large or small--and some of them are among the largest on the globe--were but a southern prolongation of the mainland of Asia. But so far from this being the case a very definite barrier is interposed. A strait, some 15 m. or so in width, and separating the two fertile but otherwise insignificant islands of Bali and Lombok, makes such a frontier as can hardly be shown to exist elsewhere. The former of these two islands belongs to the Indian Region, the latter to the Australian, and between them there is absolutely no true transition--that is, no species are common to both which cannot be easily accounted for by the various accidents and migrations that in the course of time must have tended to mingle the productions of islands so close to one another. The faunas of the two are as absolutely distinct as those of South America and Africa, and it is only because they are separated by a narrow strait instead of the broad Atlantic that they have become so slightly connected by the interchange of a few species and genera.

"Now, first, of the forms of birds which are prevalent throughout the Indian Region, but are entirely wanting in the Australian, we have at once the bulbuls (_Ixidae_), very characteristic of most parts of Africa and Asia, including the sub-group _Phyllornithinae_, which is peculiar to the Indian Region; the widely-spread families of barbets (_Megalaeminae_) and vultures (_Vulturidae_); and the pheasants (_Phasianidae_), which attain so great a development in various parts of the Asiatic continent and islands that there must their home be regarded as fixed. Some naturalists would add the finches (_Fringillidae_), rightly if we assume that the _Ploceidae_ or weavers constitute a separate family. Then, of forms which are but weakly represented, we have the otherwise abundant thrushes (_Turdidae_), and, above all, the woodpeckers (_Picidae_), of which only very few species, out of 400, just cross the boundary and occur in Lombok, Celebes or the Moluccas, but are unknown elsewhere in the region."

But the Australian region is also remarkable for its ornithic singularity. All the existing Ratitae (with the exception of the ostriches of Africa and South America, belonging to the genera _Struthio_ and _Rhea_, and comprising at most but five species) are found in Austrogaea and nowhere else. Of the Passeres the honey-suckers (_Meliphagidae_) are most characteristic, and, abounding in genera and species, extend to almost every part of the region, yet only one species of _Ptilotis_ oversteps its limits, crossing the sea from Lombok to Bali. Other peculiar families are much more confined. But the positive characteristics of the region as a whole are not its peculiar forms alone; there are at least four families which, being feebly represented elsewhere, here attain the maximum of development. Such are the thick-headed shrikes (_Pachycephalidae_), the caterpillar-eaters (_Campephagidae_), the flower-peckers (_Dicaeidae_), and the swallow-flycatchers (_Artamidae_). Besides these, three or perhaps four groups, though widely distributed throughout the world, arrive in the Australian region at their culmination, presenting an abundance of most varied forms. These are the weaver-birds (_Ploceidae_), and the moreporks (_Podargidae_), but especially the kingfishers (_Alcedinidae_) and the pigeons (_Columbidae_), the species belonging to the two last obtaining in this region a degree of prominence and beauty which is elsewhere unequalled.

The boundaries of the subregions are not well defined.

The _New Zealand Subregion_, considered by Professors Newton and Huxley and various other zoogeographers as deserving the rank of a region, is, and to all appearance has long been, more isolated than any other portion of the globe. Besides the three larger islands numerous satellites belong to the subregion, as Lord Howe, Norfolk and Kermadec islands, with the Chatham, Auckland and Macquarie groups. The main affinities of the avifauna are, of course, Australian. The most extraordinary feature is unquestionably the former existence of the gigantic Dinornithes or moas (q.v.) and, another family of Ratitae, the weird-looking kiwis or Apteryges, which are totally unlike any other existing birds. Of other peculiar genera it will suffice to mention only the more remarkable. _Rallidae_ present the very noteworthy woodhens, _Ocydromus_, and the takahe, _Notornis_, which is almost extinct. The widely-spread plovers, _Charadriidae_, have two not less singular generic developments, _Thinornis_, and the extraordinary wrybill, _Anarhynchus_. There is an owl, type of the genus _Sceloglaux_. Of parrots, _Stringops_, the kakapo or owl-parrot, is certainly peculiar, while _Nestor_ constitutes a peculiar subfamily of the brush-tongued parrots or _Trichoglossidae_. _Xenicus_ and _Acanthositta_ form a little family of truly mesomyodean Passeres Clamatores. Of the _Meliphagidae_ the genera _Prosthemadera_, _Pogonornis_ and _Anthornis_ are peculiar. The starlings, _Sturnidae_, are represented by _Callaeas_, _Creadion_ and the very abnormal _Heterolocha_. The gallinaceous birds are represented by a quail, _Coturnix novae zealandiae_, now exterminated. A large flightless goose, _Cnemiornis_, allied to the Australian _Cereopsis_, and the gigantic rapacious _Harpagornis_, have died out recently, with the moas. In all, there is a wonderful amount of specialization, though perhaps in a very straight line from generalized forms; but the affinity to Australian or Polynesian types is in many cases clearly traceable, and it cannot be supposed but that these last are of cognate origin with those of New Zealand. A very long period of isolation must have been required to produce the differences so manifestly to be observed, but a few forms seem at rare intervals to have immigrated, and this immigration would appear to be kept up to our own day, as shown by the instance of _Zosterops lateralis_, which is said to have lately made its first appearance, and to have established itself in the country, as well as by the fact of two cuckoos, the widely-ranging _Eudynamis taitensis_ and _Chrysococcyx lucidus_, which are annual visitors.

_Polynesia_ forms, of course, part of Austrogaea. Its extent is so vast that it necessarily contains some peculiar, outlying forms, so to say forgotten, which in their long-continued isolation have specialized themselves. For instance, the kagu (_Rhinochetus_) of New Caledonia, a queerly specialized form with Gruine affinities pointing only to South America. The toothbilled pigeon (_Didunculus_) is restricted to Samoa. Most interesting is the avifauna of the Sandwich islands; entirely devoid of Psittaci and of Coraciiformes, these islands show an extraordinary development of its peculiar family _Drepanidae_, which are probably of South or Central American descent. _Acrulocercus_ is a Meliphagine, and a peculiar genus. There are a raven (_Corvus_), a coot (_Fulica_), the well-known Sandwich island goose (_Bernicla sandvicensis_), now very commonly domesticated in Europe; and some flycatchers and thrushlike birds.

The _Australian Subregion_ comprises Australia and Tasmania. In the north it is influenced, of course, by its proximity to Papuasia, whence there is a considerable admixture of genera which do not proceed beyond the tropics, and of these _Casuarius_ is a striking example. The Cape York peninsula practically belongs to Papuasia. As a whole, Australia is rich in parrots, of which it has several very peculiar forms, but Picarians in old-fashioned parlance, of all sorts--certain kingfishers excepted--are few in number, and the pigeons are also comparatively scarce, no doubt because of the many arboreal predaceous marsupials. The continent, however, possesses the two important genera of the _Pseudoscines_, namely the lyre-birds (_Menura_) and the scrub-birds (_Atrichia_). Among the more curious forms of other land-birds may be especially mentioned the _Megapodiidae_, _Lipoa_ and _Talegallus_, the rail _Tribonyx_ and _Pedionomus_, which represents the otherwise palaeotropical _Turnices_ in Australia. The presence of bustards (_Eupodotis_) is a curious example of interrupted distribution, since none other of the _Otididae_ are found nearer than India. The Ratitae are represented by two species of emeu (_Dromaeus_), besides the cassowary of Cape York peninsula, and the extinct _Dromornis_ and _Genyornis_ with its enormous skull.

The _Papuan Subregion_, chiefly New Guinea with its dependencies, the Timor group of islands, the Moluccas and Celebes. On the whole its avifauna presents some very remarkable features. Its most distinctive characteristic is the presence of the birds of paradise, which are almost peculiar to it; for, granting that the bower-birds, _Chlamydodera_ and others, of Australia, belong to the same family, they are far less highly specialized than the beautiful and extraordinary forms which are found, within very restricted limits, in the various islands of the subregion. Another chief feature is the extraordinary development of the cassowaries, the richness and specialization of the kingfishers, parrots, pigeons, honey-suckers and some remarkable flycatchers. It has several marked deficiencies compared with Australia, among which are the babblers (_Timeliidae_), weaver birds (_Ploceidae_), the _Platycercinae_ among parrots, diurnal birds of prey and the emeus. As a whole, the birds of Papua are remarkable for their brilliance of plumage, or their metallic colouring. The birds of paradise, the racquet-tailed kingfishers, _Tanysiptera_, the largest and smallest of parrots, _Calyptdrhynchiis_ and _Nasiterna_, and the great crowned pigeons, _Goura_, are very characteristic; and so are the various Megapodes.

(B) NEOGAEA, or the _Neotropical region._--Excepting towards the north, where, in Mexico, it meets, and inosculates with the Nearctic subregion, the boundaries of the Neotropical region are simple enough to trace, comprehending as it does the whole of South America and all Central America; besides including the Falkland islands to the south-east and the Galapagos under the equator to the west, as well as the Antilles or West India islands up to the Florida channel.

Owing to the comparatively scanty number of harmful mammalian types, the birds play a considerable part in this large region, and some authorities consider its avifauna the richest in the world. The entire number of species amounts to about 3600. Of these 2000, or a good deal more than half, belong to the order Passeriformes. But the characteristic nature of the avifauna is more clearly brought out when we learn that of the 2000 species just mentioned only about 1070 belong to the higher suborder of Oscines, that means to say, nearly one-half belong to the lower suborder Clamatores. This is a state of things which exists nowhere else; for except in Australia, where a few indigenous and peculiar low non-Oscines are found, and in the Nearctic country, whither one family of Clamatores, viz. the _Tyrannidae_, has evidently been led by the geographical continuity of its soil with that of the Neotropical region, such forms do not occur elsewhere. Accordingly their disproportionate prevalence in South America points unerringly to the lower rank of the avifauna of the region as a whole, and therefore to the propriety of putting it next in order to that of the Australian region, the general fauna of which is admittedly the lowest in the world. Huxley has urged with his wonted perspicuity the alliance of these two regions as _Notogaea_, basing his opinion, besides other weighty evidence, in great measure on the evidence afforded by the two main sections of the Galli, viz. the _Peristeropodes_ and the _Alectoropodes_, the former composed of the families _Megapodiidae_, almost wholly Australian, and the _Cracidae_, entirely Neotropical. (Cf. _P.Z.S._, 1868. pp. 294-319.)

Leaving, however, this matter as in some degree hypothetical, we have as genera, families, or perhaps even larger groups, a great many very remarkable forms which are characteristic of, or peculiar to, the Neotropical region in part, if not as a whole. Of families we find twenty-three, or maybe more, absolutely restricted thereto, besides at least eight which, being peculiar to the New World, extend their range into the Nearctic region, but are there so feebly developed that their origin may be safely ascribed to the southern portion of America. First in point of importance comes the extraordinarily beautiful family of humming-birds (_Trochilidae_), with nearly 150 genera (of which only three occur in the Nearctic region) and more than 400 species. Then the tyrants (_Tyrannidae_), with more than seventy genera (ten of which range into the northern region), and over 300 species. To these follow the tanagers (_Tanagndae_), with upwards of forty genera (only one of which crosses the border), and about 300 species; the piculules (_Dendrocolaptidae_), with as many genera, and over 200 species; the ant-thrushes, (_Formicariidae_), with more than thirty genera, and nearly 200 species; together with other groups which, if not so large as those just named, are yet just as well defined, and possibly more significant, namely, the tapaculos (_Pteroptochidae_), the toucans (_Rhamphastidae_), the jacamars (_Galbulidae_), the motmots (_Monotidae_), the todies (_Todidae_), the trumpeters (_Psophiidae_), and the screamers (_Palamedeidae_); besides such isolated forms as the seriema (_Cariama_), and the sun-bittern (_Eurypyga_).

The nature of the South American avifauna will perhaps become still more evident if we arrange the characteristic members as follows:--

1. Birds which are restricted to, probably indigenous of the region: _Rhea_; _Palamedea_ and _Chauna_, the screamers; _Tinami_; _Psophia, Dicholophus, Eurypyga, Heliornis_ of the Gruiform assembly; _Thinocorys_ and _Attagis; Cracidae; Opisthocomus_; of parrots _Ara_ and _Conurus_ with their allies; _Monotidae_, incl. _Todus; Steatornis; Galbulinae_ and _Bucconinae; Rhamphastidae; Formicariidae, Pteroptochidae_, and of the _Tyrannidae_ the _Cotinginae_.

2. Birds which are indigenous, but extend far into North America: _Cathartae, Trochilidae, Tyrannidae_.

3. Birds which are originally immigrants from North America: _Podicipedidae_, with the flightless _Centropelma_ on Lake Titicaca; _Ceryle_, the only genus of kingfishers in the New World; all the _Oscines_.

More or less cosmopolitan groups like herons, _Falconidae, Anseres, Columbae, &c._, and circumtropical families like _Parridae, Trogonidae, Capitonidae_, are to be excluded from these lists as indifferent. The differences between the Neotropical avifauna and that of North America are fundamental and prove the independence or superior value of the Neotropical region as one of the principal realms.

It is difficult to subdivide the Neotropical region into subregions; the best suggestion is that of Newton: _Antillean_, with the exception of the islands of Trinidad and Tobago, as well as those which lie on the northern coast of South America; _Patagonian_, including Chile and part of Peru; _Columbian_, comprising the rest of the continent and also Central America.

The _Antillean Subregion_ is in many respects one of the most suggestive and interesting, comparatively small though it be. For narrow as are the channels between Cuba and the opposite coast of Central America, between the Bahamas and Florida, and between Grenada and Tobago, the fauna of the Antillean chain, instead of being a mixture of that of the almost contiguous countries, differs much from all, and exhibits in some groups a degree of speciality which may be not unfitly compared with that of oceanic islands. Except such as are of coral formation, the Antilles are hilly, not to say mountainous, their summits rising in places to an elevation of 8000 ft., and nearly all, prior to their occupation by Europeans, were covered with luxuriant forest, which, assisting in the collection and condensation of the clouds brought by the trade winds, ensured its own vitality by precipitating frequent and long-continued rains upon the fertile soil. Under such conditions we might expect to find an extremely plentiful animal population, one as rich as that which inhabits the same latitudes in Central America, not many degrees farther to the west; but no instance perhaps can be cited which shows more strikingly the difference between a continental and an insular fauna, since, making every allowance for the ravages of cultivation by civilized man, the contrary is the case, and possibly no area of land so highly favoured by nature is so poorly furnished with the higher forms of animal life. Here, as over so large a portion of the Australian region, we find birds constituting the supreme class--the scarcity of mammals being accounted for in some measure as a normal effect of insularity.

There is one peculiar subfamily, _Todinae_, represented by only four species of _Todus_. We note the absence of _Ratitae, Tinami, Cracidae, Rhamphastidae_, and any of those gruiform genera which are so characteristic of the continent. There is no family of birds common to the Nearctic area and the Antillean subregion without occurring also in other parts of the Neotropical region, a fact which proves its affinity to the latter.

The _Patagonian Subregion_, most extratropical, is naturally devoid of a good many typically tropical birds, or these are but poorly represented, for instance _Caerebidae, Mniotiltidae, Tanagridae, Vireonidae_. On the other hand some of the most characteristic features of the whole region are here well represented, e.g. _Rhea, Tinami, Chauna, Dicholophus, Attagis, Pteroptochidae_, and indeed therein we find some of the best evidence of the antiquity of its population, both recent and extinct (cf. the numerous fossils of the Santa Cruz formation), and also the nearest resemblance to the fauna of Austrogaea.

(C) ARCTOGAEA is Huxley's well-chosen term for all the rest of the world (including the Nearctic, Palaearctic, Indian and Ethiopian regions of P.L. Sclater) in opposition to Notogaea. Faunistically, although not geographically, the Nearctic and Palaearctic areas must form the two subdivisions of one great unit, for which the "Holarctic region" is now the generally accepted term.

The HOLARCTIC REGION, comprising North America and the extratropical mass of land of the Old World, may from an ornithological point of view be characterized by the Colymbi, _Alcidae, Gallidae_ or Alectoropodous Galli, and the Oscines, which have here reached their highest development; while Ratitae, Tinami, Psittaci, and non-Oscine Passeres (with the exception of _Tyrannidae_ extending into North America and _Conurus carolinensis_) are absent.

_Nearctic Subregion._--The close affinity of North America with the Palaearctic avifauna becomes at once apparent if we exclude those groups of birds which we have good reason to believe have their original home in the Neotropical region, notably numerous _Tyrannidae_, humming-birds and the turkey-buzzards.

The following groups may be mentioned as characteristic and typically American, and, since we consider them as comparatively recent immigrants into the Neotropical region, as originally peculiar to the Nearctic area: _Mniotiltidae, Vireonidae, Icteridae, Meleagris_ and various _Tetraoninae_. Restricted to and peculiar to the sub-region is only the little Oscine family of _Chamaeidae_, restricted to the coast district of California. "More than one-third of the genera of Nearctic birds are common also to the Palaearctic subregion. If we take the number of Nearctic species at 700, which is perhaps an exaggeration, and that of the Palaearctic at 850, we find that, exclusive stragglers, there are about 120 common to the two areas. Nearly 20 more are properly Palaearctic, but occasionally occur in America, and about 50 are Nearctic, which from time to time stray to Europe or Asia. This, however, is by no means the only point of resemblance. Of many genera, the so-called species found in the New World are represented in the Old by forms so like them that often none but an expert can distinguish them, and of such representative 'species' about 80 might be enumerated" (Newton, _Dict. Birds_, p. 335).

Of the many attempts to subdivide the Nearctic subregion, the same authority favours that of Dr S.F. Baird, who distinguishes between _Canadian, Alleghanian, Middle_ or Missourian, _Californian_ and _Alaskan_ provinces. Dr Hart Merriam takes the broad point of view "that the whole of extratropical North America consists of but two primary life regions, a _Boreal_ region, which is circumpolar, and a _Sonoran_ or Mexican tableland region which is unique." The first of these supports Newton's contention of the essential unity of the Nearctic and Palaearctic areas. In any case the various Nearctic subdivisions completely merge into each other, just as is to be expected from the physical configuration and other bionomic conditions of the Nort American continent.

The _Palaearctic Subregion_ is, broadly speaking, Europe and Asia, with the exception of India and China. The propriety of comprehending this enormous tract in one zoological "region" was first shown by Dr P.L. Sclater, and as regards the distribution of most classes of animals there have been few to doubt that it is an extremely natural one. Not indeed altogether so homogeneous as the Nearctic area, it presents, however, even at its extreme points, no very striking difference between the bulk of its birds. Though Japan is far removed from western Europe, and though a few generic forms and still fewer families inhabit the one without also frequenting the other, yet there is a most astonishing similarity in a large portion of their respective birds. In some cases the closest examination has failed to detect any distinction that may be called specific between the members of their avifauna; but in most it is possible to discover just sufficient difference to warrant a separation of the subjects. Nevertheless, it is clear that in Japan we have, as it were, a repetition of some of our most familiar species--the redbreast and the hedge-sparrow, for example--slightly modified in plumage or otherwise, so as to furnish instances of the most accurate representation, e.g. _Cyanopica cooki_ of Portugal and Spain, and _C. cyana_ of Amoorland and Japan.

Like the Nearctic the Palaearctic subregion seems to possess but one single peculiar family of land birds, the _Panuridae_, represented by the beautiful species known to Englishmen as the bearded tit-mouse, _Panurus biarmicus_. The entire number of Palaearctic families are, according to Newton, 67, and of the genera 323. Of these 128 are common to the Nearctic subregion. Species of 51 more seem to occur as true natives within the Ethiopian and Indian regions, and besides these 18 appear to be common to the Ethiopian without being found in the Indian, and no fewer than 71 to the Indian without occurring in the Ethiopian. To compare the Palaearctic genera with those of the Australian and Neotropical regions would be simply a waste of time, for the points of resemblance are extremely few, and such as they are they lead to nothing. It will therefore be seen from the above that next to the Nearctic are the Palaearctic has a much greater affinity to any other, a fact which might be expected from geographical considerations.

Having shown this much we have next to deal with the peculiarities of the vast Palaearctic subregion. At the lowest computation 37 genera seem to be peculiar to it, though it is certain that species of several are regularly wont to wander beyond its limits in winter seeking a southern climate. Of the peculiar genera only a few examples may be mentioned: _Eurynorhynchus_, the spoon-billed sandpiper of Siberia; _Syrrhaptes_, the sandgrouse of central Asia; _Musicicapa_ of Europe.

We distinguish between a _Siberian, Mongolian, Mediterranean_ and _European province_, none of which can be well defined. The islands of the Canaries, Madeira and the Azores belong to the Mediterranean province, and offer some peculiarities of great interest. The Azores have been monographed by F.D. Godman (_Nat. Hist. of the Azores or Western Islands_, London, 1870). There is a general tendency among these insular birds to vary more or less from their continental representatives, and this is especially shown by the former having always darker plumage and stronger bills and legs. In one instance the variation is so excessive that it fully justifies the establishment of a specific distinction. This is the case of the bullfinch of the more western of these islands (_Pyrrhula murina_), the male of which, instead of the ruddy breast of its well-known congener (_P. vulgaris_), has that part of a sober mouse-colour. A similar sombre hue distinguishes the peculiar chaffinch of the Canary Islands (_Fringilla teydea_), but to these islands as well as the Azores and Madeiras there belongs in common another chaffinch (_F. tintillon_) which, though very nearly allied to that of Mauritania (_F. spodogenia_) is perfectly recognizable, and not found elsewhere. Madeira has also its peculiar golden-crested wren (_Regulus maderensis_), and its peculiar pigeon (_Columba trocaz_), while two allied forms of the latter (_C. laurivora_ and _C. bollii_) are found only in the Canaries. Further on this subject we must not go; we can only state that Godman has shown good reason for declaring that the avifauna of all these islands is the effect of colonization extending over a long period of years, and going on now.

PALAEOTROPICAL REGION.--Much can be said in favour of combining the mostly tropical portion of the great mass of land of the Old World (excluding, of course, Austrogaea or the Australian region) into one region, for which Oscar Drude's well-chosen term "palaeotropical" has been adopted (cf. Bronn's _Thierreich, System Part._ p. 296, 1893). This region naturally comprises the African and Indian areas, conformably to be called subregions.

Both subregions possess, besides others, the following characteristic birds: Ratitae, viz. _Struthio_ in Africa and Arabia, fossil also in the Sivalik Hills, and _Aepyornithidae_ in Madagascar; _Pittidae, Bucerotinae_ and _Upupinae_, of which _Upupa_ itself in India, Madagascar and Africa; _Coraciidae; Pycnonotidae_ or bulbuls; _Trogonidae_, of which the Asiatic genera are the less specialized in opposition to the Neotropical forms; _Vulturidae; Leptoptilus, Anastomus_ and _Ciconia_ among the storks; _Pteroclidae; Treroninae_ among pigeons. Of other families which, however, extend their range more or less far into the Australian realm, may be mentioned _Otididae_, the bustards; _Meropidae_ or bee-eaters; _Muscicapidae_ or flycatchers; _Sturnidae_ or starlings.

The _Ethiopian Subregion_ comprises the whole of Africa and Madagascar, except the Barbary States, but including Arabia; in the north-east the subregion melts into the Palaearctic between its limits still farther to the eastwards, through Beluchistan and even beyond the Indus.

So large a portion of the Ethiopian subregion lies between the tropics that no surprise need be expressed at the richness of its fauna relatively to that of the last two subregions we have considered. Between fifty and sixty so-called families of land birds alone are found within its limits, and of them at least nine are peculiar; the typical genera of which are _Buphaga, Euryceros, Philepitta, Musophaga, Irrisor, Leptosoma, Colius, Serpentarius, Struthio, Aepyornis_. It is singular that only the first three of them belong to the order _Passeriformes_, a proportion which is not maintained in any other tropical region. The number of peculiar genera, besides those just mentioned, is too great for them to be named here; some of the most remarkable on the continent are: _Balaeniceps_, the whale-headed heron; _Balaearica_, the crowned crane; _Podica_, finfoot; _Numida_ and allied genera of guinea fowls.

The natural division of the subregion is that into an African and a Madagascar province. Subdivision of the continental portion is beset with great difficulties, and none of the numerous attempts have proved long-lived. The forest-clad basin of the Congo, with the coastal districts of the bay of Guinea, seem to form one domain in opposition to the rest.

The Malagasy province comprises, besides Madagascar, the Mascarene, Comoro and Seyehelle islands. It may be safely deemed the most peculiar area of the earth's surface, while from the richness and multifariousness of its animal, and especially of its ornithic population, New Zealand cannot be compared with it. In A. Grandidier's magnificent _Histoire physique, naturelle et politique de Madagascar_, vol. xii. (Paris, 1875-1884), are enumerated 238 species as belonging to the island, of which 129 are peculiar to it, and among those are no fewer than 35 peculiar genera. _Euryceros_ of the Oscines, and _Philepitta_ of the Clamatores, are remarkable enough to form the types of Passeriform families, and _Mesites_ half-way between Galli and Gruiformes is of prime importance. The Passerine _Falculia_, with its recently extinguished allies _Fregilupus_ and _Necropsar_ of the Mascarenes; the Coraciine _Brachypteracias_, _Atelornis_ and _Geobiastes_, are very abundant, while _Heliodilus_ is an owl belonging to that subfamily which is otherwise represented only by the widely-spread barn owl, _Strix flammea_. Lastly must be noted the extinct tall Ratite species of _Aepyornis_ with its several fancy genera. But, as Newton charmingly puts it (_Dict Birds_, p. 353), the avifauna of Madagascar is not entirely composed of such singularities as these. We have homely genera, even among the true _Passeres_, occurring there--such as _Alauda, Acrocephalus, Motacilla_ and _Pratincola_, while the _Cisticola madagascariensis_ is only distinguishable from the well-known fan-tailed warbler, _C. schoenicola_ of Europe, Africa and India by its rather darker coloration. But there are also species, though not Passerine, which are absolutely identical with those of Britain, the barn owl, common quail, pigmy rail, and little grebe or dabchick, all of them common and apparently resident in the island. Mauritius had the dodo (q.v.), _Lophopsittacus_ and _Aphanapteryx_. Rodriguez had the solitaire, _Necropsittacus_ and _Necropsar_. Bourbon or Reunion had _Fregilupus_.

Some of the Malagasy avifauna is certainly ancient, aboriginal, and even points to India; other forms indicate clearly their African origin; while, lastly, such strikingly characteristic Indo-African birds as hornbills are unaccountably absent.

The _Oriental Subregion_ comprises all the countries and numerous islands between the Palaearctic and Australian areas; it possesses upwards of seventy families, of which, however, only one is peculiar, but this family, the _Eurylaemidae_ or broadbills, is of great importance since it represents all the _Subclamatores_. Of the many characteristic birds may be mentioned _Pycnonotidae_ or bulbuls, of which the _Phyllornithinae_ are peculiar, _Campephagidae_ or cuckoo shrikes, _Dicruridae_ or drongos, _Nectariniidae_ or sunbirds; pheasants, together with _Pavo_ and _Gallus_. Some of the similarities to the Ethiopian and the great differences from the Australian avifauna have already been pointed out. Naturally no line whatever can be drawn between the Oriental and the Palaearctic subregions, and many otherwise essentially Indo-Malayan families extend far into the Australian realm, far across Wallace's line, whilst the reverse takes place to a much more moderate extent. Certainly the Oriental area, in spite of its considerable size, cannot possibly claim the standing of a primary region. It is a continuation of the great Arctogaea into the tropics.

Following H.J. Elwes we subdivide the whole subregion into a Himalo-Chinese, Indian and Malayan province. These divisions had the approval of W.T. Blanford, who proposed the terms Cis-and Trans-gangetic for the two first. The Himalo-Chinese or Trans-gangetic province shows the characteristics of its avifauna also far away to the eastward in Formosa, Hainan and Cochin China, and again in a lesser degree to the southward in the mountains of Malacca and Sumatra. Indo-China is especially rich in _Eurylaemidae_, China proper and the Himalayas in pheasants.

The Indian or Cisgangetic province is the least rich of the three so far as peculiar genera are concerned.

The Malayan province comprising the Malay islands, besides the Malay peninsula, and the very remarkable Philippines, possess an extraordinary number of peculiar and interesting genera.

The influence of the Australian realm is indicated by a Megapode in Celebes, another in Borneo and Labuan, and a third in the Nicobar islands (which, however, like the Andamans, belong to the Indian province), but there are no cockatoos, these keeping strictly to the other side of Wallace's line, whence we started on this survey of the world's avifauna.

D. CLASSIFICATION OF BIRDS

Fuerbringer's great work, published in the year 1888 by the _Natura Artis Magistra_ Society of Amsterdam, enabled Gadow not only to continue for the next five years the same lines of morphological research, but also further to investigate those questions which were still left in abeyance or seemed to require renewed study. The resulting "classification is based on the examination, mostly autoptic, of a far greater number of characters than any that had preceded it; moreover, they were chosen in a different way, discernment being exercised in sifting and weighing them, so as to determine, so far as possible, the relative value of each, according as that value may vary in different groups, and not to produce a mere mechanical 'key' after the fashion become of late years so common" (Newton's _Dictionary of Birds_, Introduction, p. 103). It is not the quantity but the quality of the anatomical and bionomic characters which determines their taxonomic value, and a few fundamental characters are better indications of the affinities of given groups of birds than a great number of agreements if these can be shown to be cases of isomorphism or heterophyletic, convergent analogy. Nature possesses three great educational or developmental schools--terrestrial, aquatic and aerial life. Each of these affords animal, vegetable or mixed diet. Animal diet implies the greatest variety with regard to locality and the modes of procuring the food. Each of these schools impresses its pupils, in the case of the birds, with its own stamp, but there are many combinations, since in the course of phyletic development many a group of birds has exchanged one school for another. Originally terrestrial groups have taken to an entirely aquatic life, and _vice versa_; others, originally endowed with the power of flight, have become, or are transforming themselves into, absolutely cursorial forms; some members of one group live entirely on seeds, while others have become fierce fishers, and so forth. Only by the most careful inquiry into their history can their relationship or pedigree be unravelled. A statement may now be given of Gadow's classification of birds, in which the extinct forms have been intercalated so far as possible. The few characters assigned to the various groups are sufficiently diagnostic when taken together, although they are not always those upon which the classification has been established:--

CLASS AVES

I. Sub-class ARCHAEORNITHES.--The three fingers and their metacarpals remain separate, each with a claw. Well-developed remiges. Both jaws with alveolar teeth. Amphicoelous. Caudal vertebrae more than thirteen, without a pygostyle, but with about twelve pairs of rectrices. _Archaeopteryx, A. lithographica, s. macroura_, two specimens from the upper Oolite of Solenhofen, Bavaria.

II. Sub-class NEORNITHES.--Metacarpals fused. Second finger the longest. Not more than thirteen caudal vertebrae.

I. Division RATITAE.--Terrestrial, flightless. Without sternal keel. Quadrate bone with single proximal knob. Without pygostyle. Coracoid and scapula fused. Compound rhamphotheca. Adult without apteria. With copulatory organ. A collective polyphyletic or heterogeneous group, originally cosmopolitan; with certainty existing since the Miocene.

1. Order Struthiones.--With pubic symphysis. Two toes only, third and fourth. _Struthio_, ostrich, Pliocene of Samos and of north-west India, now Africa and Arabia.

2. Order Rheae.--With long ischiadic symphysis. Three toes. _Mesembriornis_, Miocene or Pliocene of Argentina. Rhea, South America.

3. Order Casuarii.--Three toes. Aftershaft as long as the other half. _Casuarius_ and _Dromaeus_, Australian. _Hypselornis_, Pliocene of Sivalik Hills.

4. Order Apteryges.--Four toes. Bill long and slender. _Apteryx_, New Zealand.

5. Order Dinornithes.--Three or four toes. Bill short. Anterior limbs extremely reduced. _Dinornis_, numerous species, recently extinct, New Zealand.

6. Order Aepyornithes.--_Aepyornis_, recently extinct, Madagascar.

To the Ratitae belong possibly also the imperfectly known _Diatryma_, Eocene of New Mexico, _Gastornis_ and _Dasornis_, Eocene of Europe, _Genyornis_, Pleistocene of Australia.

II. Division ODONTOLCAE.--Marine, flightless, without sternal keel. Upper and lower jaws with teeth in furrows. Cretaceous epoch. _Enaliornis_, England, vertebrae chiefly biconcave; _Hesperornis_, North America, vertebrae heterocoelous.

III. Division CARINATAE.--With keeled sternum.

1. Order Ichthyornithes.--Power of flight well developed. Vertebrae still amphicoelous. With small pygostyle. Incisura ischiadica. With alveolar teeth. Cretaceous of Kansas. _Ichthyornis, Apatornis_.

2. Order Colymbiformes.--Plantigrade, nidifugous, aquatic. All toes webbed, fourth largest, hallux short; metatarsus laterally compressed; tibia with high, pyramidal crest. Bill straight, pointed, with simple sheath.

Sub-order 1. COLYMBI, Divers. Front toes completely webbed. Holarctic. _Colymbus_.

Sub-order 2. PODICIPEDES, Grebes. Toes lobated. Cosmopolitan.

3. Order Sphenisciformes.--Nidicolous, marine. Flightless, wings transformed into rowing paddles. SPHENISCI, penguins. Antarctic and southern temperate coasts. Since the Eocene.

4. Order Procellariiformes.--Well flying, pelagic, nidicolous. Hallux absent or vestigial. Rhamphotheca compound. Cosmopolitan. TUBINARES, petrels and albatrosses.

5. Order Ciconiiformes.--Swimmers or waders. Desmognathous, without basipterygoid processes; with one pair of sterno-tracheal muscles.

Sub-order 1. STEGANOPODES.--Well flying, aquatic, nidicolous; with all the four toes webbed together. Rhamphotheca compound; cosmopolitan. _Phaethon_, tropic-bird; _Sula_, gannet; _Phalacrocorax_, cormorant and _Plotus_, snake-bird; _Fregata_, frigate-bird; Pelecanus. Here also _Pelagornis_, Miocene of France; _Argillornis_ and probably _Odontopteryx_ from the London Clay.

Sub-order 2. ARDEAE.--Piscivorous, nidicolous, waders; with complicated hypotarsus and with long cervical apteria. _Ardeidae_, cosmopolitan; including _Cancroma_, Neotropical, _Balaeniceps, Scopidae_, Ethiopian. _Proherodius_, Eocene of England.

Sub-order 3. CICONIAE.--Zoophagous, nidicolous, waders; with simple hypotarsus and without cervical apteria. Cosmopolitan. _Ciconiidae_, storks. _Ibidae_, ibises and spoonbills. _Propelargus_, Oligocene.

Sub-order 4. PHOENICOPTERI.--Flamingos. Nidifugous, waders; with simple hypotarsus and without cervical apteria. Front toes completely webbed; hallux very short or absent; feed chiefly on small aquatic invertebrates. _Phoenicopterus_, cosmopolitan. Oligocene _Elornis_ and, allied, _Palaelodus_.

6. Order Anseriformes.--Desmognathous, nidifugous; with two pairs of sterno-tracheal muscles, with complete basipterygoid processes and with a penis.

Sub-order 1. PALAMEDEAE.--Screamers. Ribs without uncinate processes. Hypotarsus simple. Neotropical. _Chauna, Palamedea_.

Sub-order 2. ANSERES.--Family _Anatidae_. Hypotarsus complex. _Anser, Anas, Cygnus_, since Miocene. _Cnemiornis_, Pleistocene, New Zealand, flightless.

7. Order Falconiformes.--Birds of prey. Carnivorous, desmognathous, nidicolous, without functional caeca. Terrestrial, aerial.

Sub-order 1. CATHARTAE.--American vultures. With nares perviae. _Cathartes_, turkey buzzards, _Sarcorhamphus gryphus_, condor _Gypagus papa_, king vulture.

Sub-order 2. ACCIPITRES.--With nares imperviae. _Serpentariidae_, secretary-bird, Ethiopian; Miocene, France. _Vulturidae_, Old World vultures, excluding Australia. _Falconidae_, cosmopolitan, since the Eocene. _Harpagornis_, Pleistocene, New Zealand; _Lithornis_, Eocene, England. _Pandionidae_, ospreys or fish hawks, cosmopolitan.

8. Order Tinamiformes.--Nidifugous, with incisura ischiadica, without pygostyle. Herbivorous, terrestrial, neotropical. _Crypturi_, tinamous.

9. Order Galliformes.--Schizognathous, herbivorous, terrestrial. With ten functional remiges. With strong spinae sterni.

Sub-order 1. MESITES.--Without basipterygoid processes, and with large spina interna. _Mesites_, Madagascar.

Sub-order 2. TURNICES.--Hemipodes or button-quails. Nidifugous; vomer large; sternum without processus obliqui. Hallux absent or vestigial. Old World. _Turnix, Pedionomus_.

Sub-order 3. GALLI.--With large spina communis, and with large processus obliqui. Hallux functional. _Megapodiidae_, Australian region. _Cracidae_, curassows and guans, neotropical. _Gallidae_, cosmopolitan.

Sub-order 4. OPISTHOCOMI.--Arboreal, with long spina externa; without basipterygoid processes. _Opisthocomus_ hoatzin, Guiana, Venezuela and Amazon countries.

10. Order Gruiformes. Legs of the wading type. Without basipterygoid processes. Without spina interna. Nidifugous. Essentially Schizognathous. _Rallidae_, cosmopolitan, since Oligocene. _Rallus, Fulica, Ocydromus, &c., Gallinula nesiotis_, Tristan d'Acunha, flightless. _Notornis_, New Zealand, flightless, nearly extinct. _Aptornis_, New Zealand, flightless, extinct. _Aphanapteryx_ (Mauritius) = _Erythromachus_ (Rodriguez) = _Diaphorapteryx_ (Chatham Island), flightless and recently extinct. _Gypsornis_, upper Eocene, France. _Gruidae_, cranes, cosmopolitan, allied _Phororhacos_, Tertiary of Argentina. _Dicholophidae_, cariamas, neotropical. _Otididae_, bustards, Old World. _Rhinochetidae_, kagus, New Caledonia. _Eurypygidae_, sun-bittern, neotropical. _Heliornithidae_, finfoots, tropical.

11. Order Charadriiformes.--Schizognathous. With eleven remiges, of which the terminal very short. Aquinto-cubital. Spinae sterni short, separate.

Sub-order 1. LIMICOLAE.--Nidifugous, without spina interna sterni. Hypotarsus complicated. _Charadriidae_, plovers. _Chionididae_, sheath-bill. _Glareolidae_, wading swallows and coursers. _Thinocorythidae_, seed-snipes. _Oedicnemididae_, thick-knees. _Parridae_.

Sub-order 2. LARI.--Aquatic, vomer complete. Without basipterygoid processes. Front toes webbed; hallux small or absent. Large supraorbital glands. Since Miocene. _Laridae_, gulls, cosmopolitan. _Alcidae_, auks, northern half of periarctic region.

Sub-order 3. PTEROCLES.--Sand-grouse. Nidifugous. Vomer vestigial. With large crop and caeca. Hallux vestigial or absent since Oligocene. Africa to India, and Siberia. _Pterocles_ and _Syrrhaptes_.

Sub-order 4. COLUMBAE.--Pigeons. Nidicolous. Vomer vestigial. With large crop, vestigial caeca. _Columbidae_, cosmopolitan, since Miocene. _Dididae_, flightless, recently extinct. _Didus_, dodo, Mauritius. _Pezophaps_, solitaire, Rodriguez.

12. Order Cuculiformes.--Desmognathous, nidicolous; zygodactylous, or with the outer toe reversible.

Sub-order 1. CUCULI.--Cuckoos. Quinto-cubital. _Cuculidae_, cosmopolitan. _Musophagidae_, plantain-eaters and touracos, Ethiopian since Miocene.

Sub-order 2. PSITTACI.--Parrots. Zygodactylous; aquinto-cubital. Cosmopolitan, chiefly tropical. _Trichoglossidae_, lories, Austro-Malayan. _Nestor_, New Zealand. _Cyclopsittacus, Eos, Lorius_, &c. _Psittacidae_, tongue smooth, incl. _Stringops_.

13. Order Coraciiformes.--Nidicolous. Nares imperviae, holorhinal. Downs restricted to the apteria or absent. Thirteen to fifteen cervical vertebrae. Mostly desmognathous. Deep plantar tendons connected with each other.

Sub-order 1. CORACIAE.--Either (1) with long spina externa sterni, _Coraciidae_, rollers, Old World. _Momotidae_, neotropical, motmots and todies. _Alcedinidae_, kingfishers, cosmopolitan or (2) with long spina communis. _Meropidae_, bee-eaters, Old World. _Upupidae, Upupinae_, hoopoes: palaearctic and palaeotropical. _Bucerotinae_, hornbills, palaeotropical; _Irrisorinae_, woodhoopoes, Ethiopian.

Sub-order 2. STRIGES.--Owls. Outer toe reversible. Schizognathous. Long caeca. Flexor tendons normal. Hypotarsus simple. Cosmopolitan.

Sub-order. 3. CAPRIMULGI.--Nightjars. Nocturnal. With gaping mouth. Ten remiges and ten rectrices. Spinae sterni vestigial. Caeca functional. _Steatornithidae, Steatornis_, oil-bird or guacharo, South America. _Podargidae_, Australasian, _Caprimulgidae_, cosmopolitan.

Sub-order 4. CYPSELI.--Tenth terminal remex the longest. With short spinae sterni. Without caeca. _Cypselidae_, swifts, cosmopolitan. _Trochilidae_, humming-birds, American.

Sub-order 5. COLII.--Mouse-birds. First and fourth toes reversible. Ethiopian.

Sub-order 6. TROGONES.--Trogons. Heterodactyle, first and second toes directed forwards, third and fourth backwards. Tropical. _Trogon gallicus_, Miocene of France.

Sub-order 7. PICI.--Zygodactylous. Tendon of the flexor hallucis longus muscle sending a strong vinculum to that of the flexor profundus muscle, the tendon of which goes to the third toe only. _Galbulidae_, puff-birds and jacamars, neotropical. _Capitonidae_, barbets, tropical. _Rhamphastidae_, toucans, neotropical. _Picidae_, woodpeckers, cosmopolitan, excepting Madagascar and Australian region.

14. Order Passeriformes.--Nidicolous. Aegithognathous, without basipterygoid processes. Spina externa sterni large, spina interna absent. Quinto-cubital, toes normal. Apparently since the upper Eocene.

Sub-order 1. PASSERES ANISOMYODAE.--Syrinx muscles entirely lateral or attached to the dorsal or ventral corners of the bronchial semi-rings, (1) _Subclamatores_. Deep plantar tendons connected by a vinculum. _Eurylaemidae_, broadbills, Indian and Indo-Malayan. (2) _Clamatores_. Deep flexor tendons not connected. _Pittidae_, palaeotropical. _Xenicidae_, New Zealand. _Tyrannidae_, American, _Formicariidae_, _Pteroptochidae_, neotropical.

Sub-order 2. PASSERES DIACROMYODAE.--Syrinx muscles of either side attached to the dorsal and ventral corners of the rings. Hallux strong, with a large claw, (1) _Suboscines_ with _Menura_, lyre-bird, and _Atrichia_, scrub-bird, in Australia. (2) _Oscines_, the true singing-birds, with more than 5000 recent species, are mostly divided into some thirty "families," few of which can be defined.

The fourteen orders of the Carinatae are further congregated into four "Legions":--

I. COLYMBOMORPHAE = Ichthyornithes + Colymbiformes + Sphenisciformes + Procellariiformes.

II. PELARGOMORPHAE = Ciconiiformes + Anseriformes + Falconiformes.

III. ALECTOROMORPHAE = Tinamiformes + Galliformes + Gruiformes + Charadriiformes.

IV. CORACIOMORPHAE = Cuculiformes + Coraciiformes + Passeriformes.

These four legions are again combined into two "Brigades," the first of which comprises the first and second legions, while the second brigade contains the third and fourth legions.

Thus the whole classification becomes a rounded-off phylogenetic system, which, at least in its broad outlines, seems to approach the natural system, the ideal goal of the scientific ornithologist. The main branches of the resultant "tree" may be rendered as follows:--

CORACIOMORPHAE + ODONTOLCAE..COLYMBO + PELARGO- ALECTOROMORPHAE..RATITAE MORPHAE MORPHAE \----+----/ / \----------+---------/ | NEORNITHES

The Odontolcae seem to be an early specialized offshoot of the Colymbo Pelargomorphous brigade, while the Ratitae represent a number of side branches of early Alectoromorphae. The Ratitae branched off, probably during the Eocene period, from that still indifferent stock which gave rise to the Tinami + Galli + Gruiformes, when the members of this stock were still in possession of those archaic characters which distinguish Ratitae from Carinatae. It follows that new groups of Ratitae can no longer be developed since there are no Carinatae living which still retain so many low characters, e.g. configuration of the palate, precoracoid, pelvis, intestinal convolutions, copulatory organ, &c. Loss of the keel is co-ordinated with the power of using the forelimbs for locomotion; although a "Ratite" character, it is not sufficient to turn a _Notornis, Cnemiornis_ or _Stringops_, not even a _Phororhacos_ into a member of the Ratitae.

Another branch of the Alectoromorphae, in particular of the Galliformes, when these were still scarcely separated from the Gruiformes, especially rail-like birds, leads through Opisthocomi to the Cuculiformes. These are, again in an ascending direction, connected with the Coraciiformes, out of which have arisen the Passeriformes, and these have blossomed into the Oscines, which, as the apotheosis of bird life, have conquered the whole inhabitable world. (H. F. G.)

FOOTNOTES:

[1] Treviranus, _Biologie oder Philosophie der lebenden Natur_, vol. ii. cap. 4, Sec. 2 (Goettingen, 1803).

[2] F. Tiedemann, _Anatomie und Naturgeschichte der Voegel_, vol. ii Sec.Sec. 127-255 (Heidelberg, 1814).

[3] L.K. Schmarda, _Die geographische Verbreitung der Thiere_ (Wien, 1853).

[4] P.L. Sclater on the general geographical distribution of the members of the class "Aves," 2. _Linn. Soc._ ii. pp. 130-145, 1858.

[5] A.R. Wallace, _The Geographical Distribution of Animals, with a study of the Relations of Living and Extinct Faunas as elucidating the Past Changes of the Earth's Surface_, 2 vols. (London, 1876).

[6] T.H. Huxley, "On the Classification and Distribution of the Alectoromorphae," _P.Z.S._, 1868, pp. 313-319.

[7] The following old-fashioned rough computation may serve as an indication of the relative size of the orders and suborders of recent birds:--

Ratitae 20 Charadriiformes 650 (incl. Columbae Colymbiformes 20 350) Sphenisciformes 15 Cuculiformes 600 (incl. Psittaci Procellariiformes 90 400) Ciconiiformes 150 Coraciiformes 1600 (incl. Trochili Anseriformes 150 and Pici) Falconiformes 360 Passeres Clamatores 1000 Tinamiformes 40 Passeres Oscines 5000 Galliformes 370 ------ Gruiformes 250 Total about 10,300 species

BIRD-LOUSE, any small flat degenerate wingless neuropterous insect of the group Mallophaga, parasitic upon birds and mammals and feeding upon dermal excretions or upon the softer parts of hair and feathers. The term "biting-lice" is sometimes given to these parasites, in allusion to the mandibulate character of their mouth-parts, which serves to distinguish them at once from the true lice of the order Rhynchota in which the jaws are haustellate.

BIRD'S-EYE, a name applied to various small bright flowers, especially those which have a small spot or "eye" in the centre. The primula is thus spoken of, on account of its yellow centre, also the adonis, or "pheasant's eye," and the blue veronica, or germander speedwell. The word is also applied to a sort of tobacco, in which the stalks (of a mottled colour) are cut up together with the leaves. From a similar sense comes the phrase "bird's-eye maple," a speckled variety of maple-wood, or the "bird's-eye handkerchief" mentioned in Thackeray's novels.

BIRDSNESTING, a general term for the pursuit of collecting and preserving birds' eggs, with or without the nests themselves. The nests and eggs of wild birds are nowadays protected by local laws almost everywhere in both Great Britain and the United States. By law they may be taken for scientific purposes only, by special licence. In order not to interfere seriously with breeding it is customary to take but one egg from a nest, and, if the nest itself be taken, to wait until the young birds have left it. Every egg, unless "hard-set," should be blown as soon as removed from the nest. This is done by opening a small hole in its side by means of a drill with a conical head, manufactured for the purpose, a minute hole for the insertion of the drill-head having first been made in the shell with a needle, which is then used to stir up the contents, so that they shall flow easily. A blow-pipe with a curved mouth is then inserted, the egg is held hole downwards, and the contents blown out. The old-fashioned method of making two holes in the egg is thus superseded. Should the egg be "hard-set" a somewhat larger hole is made and its edges reinforced with layers of paper pasted round them. Minute forceps are then introduced and the embryo cut into pieces small enough to pass through the hole. The inside of the egg is then rinsed out with clean water, and also before being placed in the cabinet, with a solution of corrosive sublimate, which prevents decay and consequent discoloration of the inner membrane. Finally the egg is placed with the hole downwards upon a sheet of white blotting-paper to dry. The authentication of the eggs is the most important duty of an egg-collector, next to identifying the specimens. According to some the best method is to mark with a fine pen on the egg itself the variety, scientific name, locality of nest, date of taking and the initials of the collector, as well as a reference to his note-book or catalogue. Others advocate keeping the authentication separate with only a numbered reference on the egg itself. Eggs should not be transported in bran or sawdust, but in strong wool-lined boxes. The best cabinets are fitted with drawers, pulled out to inspect the eggs, but at other times closed to preserve them from the light, which is injurious to their delicate colouring. When an entire nest is taken it should be disinfected with hyposulphite of soda or insect-powder.

See _Birdnesting and Bird-Skinning_, by E. Newman (London, 1888); _The Young Collector's Handbook of British Birds' Nests and Eggs_, by W.H. Bath (London, 1888); _Birds' Nests, Eggs and Egg-Collecting_, by R. Kearton (London, 1890); _British Birds' Eggs and Nests_, by J.C. Atkinson (London, 1898); _Nests and Eggs of North American Birds_, by Ernest Ingersoll (1880-1881).

BIRDS OF PARADISE, a group of passerine birds inhabiting New Guinea and the adjacent islands, so named by the Dutch voyagers in allusion to the brilliancy of their plumage, and to the current belief that, possessing neither wings nor feet, they passed their lives in the air, sustained on their ample plumes, resting only at long intervals suspended from the branches of lofty trees by the wire-like feathers of the tail, and drawing their food "from the dews of heaven and the nectar of flowers." Such stories obtained credence from the fact that so late as the year 1760, when Linnaeus named the principal species _apoda_, or "footless," no perfect specimen had been seen in Europe, the natives who sold the skins to coast traders invariably depriving them of feet and wings. The birds now usually included under this name belong to the family _Paradiseidae_, closely allied to the crows. The largest is the great emerald bird (_Paradisea apoda_), about the size of the common jay. Its head and neck are covered with short thick-set feathers, resembling velvet pile, of a bright straw colour above, and a brilliant emerald green beneath. From under the shoulders on each side springs a dense tuft of golden-orange plumes, about 2 ft. in length, which the bird can raise at pleasure, so as to enclose the greater part of its body. The two centre tail feathers attain a length of 34 in., and, being destitute of webs, have a thin wire-like appearance. This splendid plumage, however, belongs only to the adult males, the females being exceedingly plain birds of a nearly uniform dusky brown colour, and possessing neither plumes nor lengthened tail feathers. The young males at first resemble the females, and it is only after the fourth moulting, according to A.R. Wallace, who has studied those birds in their native haunts, that they assume the perfect plumage of their sex, which, however, they retain permanently afterwards, and not during the breeding season only as was formerly supposed. At that season the males assemble, in numbers varying from twelve to twenty, on certain trees, and there disport themselves, so as to display their magnificent plumes in presence of the females. Wallace in his _Malay Archipelago_, vol. ii., thus describes the attitude of the male birds at one of those "sacaleli," or dancing parties, as the natives call them; "their wings," he says, "are raised vertically over the back, the head is bent down and stretched out, and the long plumes are raised up and expanded till they form two magnificent golden fans striped with deep red at the base, and fading off into the pale brown tint of the finely-divided and softly-waving points; the whole bird is then overshadowed by them, the crouching body, yellow head, and emerald green throat, forming but the foundation and setting to the golden glory which waves above." It is at this season that those birds are chiefly captured. The bird-catcher having found a tree thus selected for a "dancing party," builds a hut among the lower branches in which to conceal himself. As soon as the male birds have begun their graceful antics, he shoots them, one after the other, with blunt arrows, for the purpose of stunning and bringing them to the ground without drawing blood, which would injure their plumage; and so eager are those birds in their courtship that almost all the males are thus brought down before the danger is perceived. The natives in preparing the skins remove both feet and wings, so as to give more prominence to the commercially valuable tuft of plumes. They also remove the skull, and the skin is then dried in a smoky hut. The great emerald bird, so far as yet known, is only found in the Aru Islands. The lesser bird of paradise (_Paradisea minor_), though smaller in size and somewhat less brilliant in plumage, in other respects closely resembles the preceding species. It is also more common, and much more widely distributed, being found throughout New Guinea and the neighbouring islands. Its plumes are those most generally used as ornaments for ladies' head-dresses. Both species are omnivorous, feeding voraciously on fruits and insects. They are strong, active birds, and are believed to be polygamous. The king bird of paradise (_Cicinnurus regius_) is one of the smallest and most brilliant of the group, and is specially distinguished by its two middle tail feathers, the ends of which alone are webbed, and coiled into a beautiful spiral disk of a lovely emerald green. In the red bird of paradise (_Paradisea rubra_) the same feathers are greatly elongated and destitute of webs, but differ from those in the other species, in being flattened out like ribbons. They are only found in the small island of Waigiu off the coast of New Guinea. Of the long-billed paradise birds the most remarkable is that known as the "twelve-wired" (_Seleucides alba_), its delicate yellow plumes, twelve of which are transformed into wire-like bristles nearly a foot long, affording a striking contrast to the dark metallic tints of the rest of its plumage. (A. N.)

BIRDWOOD, SIR GEORGE CHRISTOPHER MOLESWORTH (1832- ), Anglo-Indian official and writer, son of General Christopher Birdwood, was born at Belgaum, in the Bombay presidency, on the 8th of December 1832. He was educated at Plymouth grammar-school and Edinburgh University, where he took his M.D. degree. Entering the Bombay Medical Service in 1854, he served in the Persian War of 1856-57, and subsequently became professor at the Grant Medical College, registrar of the university, curator of the museum, and sheriff at Bombay, besides acting as secretary of the Asiatic and Horticultural societies. His work on the _Economic Vegetable Products of the Bombay Presidency_ reached its twelfth edition in 1868. He interested himself prominently also in the municipal life of the city, where he acquired great influence and popularity. He was obliged by ill-health in 1868 to return to England, where he entered the revenue and statistics department of the India Office (1871-1902). Whilst engaged there he published important volumes on the industrial arts of India, the ancient records of the India Office, and the first letter-book of the East India Company. He devoted much time and energy to the encouragement of Indian art, on various aspects of which he wrote valuable monographs, and his name was identified with the representation of India at all the principal international exhibitions from 1857 to 1901. (See _Journal of Indian Art_, vol. viii. "The Life and Work of Sir George Birdwood.") His researches on the subject of incense (_Trans. Linn. Soc._ xxvii., 1871; _Ency. Brit._ 9th ed., "Incense," 1881; revised for the present edition by him), a good example of his mastery of detail, have made his historical and botanical account of this subject a classic. Nor can his lifelong association with journalism of the best sort be overlooked. From boyhood he was a diligent contributor of special information to magazines and newspapers; in India he helped to convert the _Standard_ into the _Times of India_, and edited the Bombay _Saturday Review_; and after his return to London he wrote for the _Pall Mall, Athenaeum, Academy_, and _Times_; and with Chenery, the editor of _The Times_, and others he took the initiative (1882) in celebrating the anniversary of Lord Beaconsfield's death as "Primrose Day" (April 19). He kept up his connexion with India by constant contributions to the Indian press; and his long friendships with Indian princes and the leading educated native Indians made his intimate knowledge of the country of peculiar value in the handling of the problems of the Indian empire. In 1887 he was created a K.C.I.E.; and, besides being given his LL.D. degree by Cambridge, he was also made an officer of the Legion of Honour and a laureate of the French Academy.

BIREJIK (Arab. _Bir_; classical, _Apamea-Zeugma_), a town of North-West Mesopotamia, in the Aleppo vilayet, altitude 1170 ft., built on a limestone cliff 400 ft. high on the left bank of the Euphrates. Pop. about 10,000, three-quarters Moslem. It is situated at one of the most important crossings of the Euphrates, where there was, in ancient times, a bridge of boats, and is now a ferry on the road from Aleppo to Urfa, Diarbekr and Mosul. Birejik corresponds actually to Apamea, which lay opposite Zeugma, and commanded the bridge with its strong castle (Kala Beda) now much ruined. The place seems to have had a pre-Seleucid existence as _Birtha_, a name which revived under Roman rule (we hear of the emperor Julian resting there on his march into Mesopotamia, A.D. 363), and is preserved to this day. The ferry over an unusually deep and narrow part of the Euphrates has been used from time immemorial in the passage from North Syria to Haran (Charrae), Edessa and North Mesopotamia, and was second in importance only to that at Thapsacus, by which crossed the route to Babylon and South Mesopotamia. Birejik was the scene of an unusually cruel massacre and persecution of Armenians in 1895.

BIREN (or BUeHREN), ERNST JOHANN (1690-1772), duke of Courland, was the grandson of a groom in the service of Duke Jacob III. of Courland, who bestowed upon him a small estate, which Biren's father inherited and where Biren himself was born. He received what little education he had at the academy of Koenigsberg, from which he was expelled for riotous conduct. In 1714 he set out to seek his fortune in Russia, and unsuccessfully solicited a place at the shabby court of the princess Sophia Charlotte, the consort of the tsarevich Alexius. Returning to Mittau, he succeeded in gaining a footing at court there through one of his sisters, who was the fancy of the ruling minister, Peter Bestuzhev, whose established mistress was no less a person than the young duchess Anne Ivanovna. During his patron's absence, Biren, a handsome, insinuating fellow, succeeded in supplanting him in the favour of Anne, and procuring the disgrace and banishment of Bestuzhev and his family. From henceforth to the end of her life Biren's influence over the duchess was paramount. On the elevation of Anne to the Russian throne in 1740, Biren, who had in the meantime married a Fraeulein von Treiden, came to Moscow, and honours and riches were heaped upon him. At the coronation (19th May) he was made grand-chamberlain, a count of the empire, on which occasion he is said to have adopted the arms of the French ducal house of Biron, and was presented with an estate at Wenden with 50,000 crowns a year. He soon made himself cordially detested by Russians of every class. He was not indeed the monster of iniquity he is popularly supposed to have been. His vices were rather of the sordid than of the satanic order. He had insinuating manners and could make himself very agreeable if he chose; but he was mean, treacherous, rapacious, suspicious and horribly vindictive. During the latter years of Anne's reign, Biren increased enormously in power and riches. His apartments in the palace adjoined those of the empress, and his liveries, furnitures and equipages were scarcely less costly than hers. Half the bribes intended for the Russian court passed through his coffers. He had landed estates everywhere. A special department of state looked after his brood mares and stallions. The magnificence of his plate astonished the French ambassador, and the diamonds of his duchess were the envy of princes. The climax of this wondrous elevation was reached when, on the extinction of the line of Kettler, the estates of Courland, in June 1737, elected him their reigning duke. He was almost as much loathed in Courland as in Russia; but the will of the empress was the law of the land, and large sums of money, smuggled into Courland in the shape of bills payable in Amsterdam to bearer, speedily convinced the electors. On her death-bed Anne, very unwillingly and only at his urgent entreaty, appointed him regent during the minority of the baby emperor, Ivan VI. Her common-sense told her that the only way she could save the man she loved from the vengeance of his enemies after her death was to facilitate in time his descent from his untenable position. Finally, on the 26th of October 1740, a so-called "positive declaration" signed by 194 dignitaries, in the name of the Russian nation, conferred the regency on Biren.

Biren's regency lasted exactly three weeks. At midnight of the 19th of November 1740 he was seized in his bedroom by his ancient rival, Field Marshal Muennich. The commission appointed to try his case condemned him (11th of April 1741) to death by quartering, but this sentence was commuted by the clemency of the new regent, Anna Leopoldovna, the mother of Ivan VI., to banishment for life at Pelin in Siberia. All Biren's vast property was confiscated, including his diamonds, worth L600,000. For twenty-two years the ex-regent disappeared from the high places of history. He re-emerges for a brief moment in 1762, when the philo-German Peter III. summoned him to court. He was now too old to be in any one's way, and that, no doubt, was the reason why Catherine II. re-established him (1763) in his duchy, which he bequeathed to his son Peter. Misfortune had chastened him, and the last years of his rule were just and even benevolent, if somewhat autocratic. He died at Mittau, his capital, on the 28th of December 1772.

See Robert Nisbet Bain, _The Pupils of Peter the Great_ (London, 1897); Christoph Hermann von Manstein, _Memoirs_ (Eng. ed., London, 1856); Claudius Rondeau, _Diplomatic Dispatches from Russia_ (St Petersburg, 1889-1892). (R. N. B.)

BIRETTA (Ital. _berretta_, Med. Lat. _biretum, birettum_, dim. of _birrus_, "a hooded cloak"; from the Fr. form _barrette_ is derived the Eng. "barret-cap"), a cap worn by the Catholic clergy. It is square and stiff, being made of a framework of cardboard covered with cloth or silk; on the top, along the sutures of the stuff, are three or four raised, board-like, arched ridges, at the junction of which in the centre is a knob or tassel (_floccus_). Its colour varies with the rank of the wearer, that of the pope being white, of the cardinals red, of bishops purple, and of the lower clergy black. It is not in the strictest sense a liturgical head-dress, its use not being confined to liturgical functions. In these functions, moreover, its use is strictly limited; e.g. it is worn at low masses by the priest only when he goes to and from the altar, at high masses also when the celebrant sits during the singing of the _Kyrie, Gloria_ and Creed, and at processions when these take place outside the church and are not sacramental, and so on.

Though the form of the biretta, devised in the 17th century, is peculiar to the Roman Church, it is but a variant of the original _biretum_, which developed in various countries into head-coverings of different shapes and significance. At the outset there was little to distinguish the _biretum_ from the _pileus_ or _pileolus_ (skull-cap), a non-liturgical cap worn by dignitaries of the Church under the mitre and even under the biretta. When the word _biretum_ first appears in the 13th century, it practically means no more than "cap," and is used as a synonym of _pileus_. As an ecclesiastical vestment the cap can be traced, under the name of _pileus_, to the 12th century; under that of _infula_, to the end of the 10th. It would seem to have been worn by the cantors as a protection against cold. The same utilitarian reason led to its introduction among the clergy generally. Thus in 1243 Pope Innocent IV. granted leave to the Benedictines of St Augustine's at Canterbury, and to those of Winchester, to wear the _pileus_ in choir. With the extension of its use, too, the custom grew up (c. 1300) of investing clerks with the _biretum_ as the symbol of the transfer of a benefice, a custom which survives, in Roman Catholic countries, in the solemn delivery of the red biretta by the head of the state to newly created cardinals, who afterwards go to Rome to receive the red hat. This red biretta is called the _zucchetto_.

This use of the _biretum_ as a symbol of office or dignity was not confined to the clergy. With various modifications of form it was worn by all persons of standing, e.g. barons, judges, and doctors and masters of the universities. The _biretum_ was also used in the investiture of laymen with office, e.g. a duke or the prefect of the city of Rome (Du Cange, _Gloss._ s.v. _birretum_). The "cap of maintenance" or "cap of estate," still borne before the British sovereign on state occasions, is a barret-cap of the type of the 14th and 15th centuries; it is of crimson velvet, turned up with ermine. By the 16th century the barret-cap had become the common head-gear of all people of substance, men and women. It was flat, square or round, sometimes with edges that could be turned up or down according to convenience, and was often elaborately decorated. By the 17th century it had given place in ordinary civil life to the brimmed hat; but in various shapes it still survives as official head-gear in many European countries: the _Barett_, worn in church by the Lutheran clergy, in the courts by German lawyers, and by the deans and rectors of the universities, the _barrette_ of French judges and barristers, the "black cap" of the English judge, and the "college cap" familiar in English and American universities, and vulgarly known as the "mortar-board."

Meanwhile the ecclesiastical developments of the _biretum_ are not without interest and significance. Originally this had been a round cap, low or moderately high, slightly bulging out at the top, and ornamented with a round knob. By the 16th century, both in England and on the continent, a tendency had begun to emphasize the ridges of the sutures and thus produce a square shape. Henceforth the evolution followed different lines. In England, in the 17th century, the square flat top began to be enlarged, forming a rim of thick stuff projecting beyond the close-fitting cap. This was the "square cap" so virulently denounced by the Puritans as a symbol of High Church Erastianism. With the triumph of High Church principles at the Restoration it was natural that a loyal clergy should desire to emphasize this squareness, and the consequent exaggeration of the square top of the cap necessitated a further stiffening. In the 18th century, accordingly, the top began to be made of a board of wood or card covered with cloth, the close-fitting cap proper retired farther from the edges, the knob developed into a long tassel, and the evolution of the modern "college cap" was complete (see fig. 1).

On the continent, meanwhile, in the Roman Catholic Church, the _biretum_ had also developed into its present characteristic form, and by a very similar process. By the end of the 16th century the square shape was everywhere prevalent; at the beginning of the 17th century cardboard was introduced to stiffen the sides and emphasize the squareness, and the actual form of the biretta, as described above, had become fixed (see fig. 2). Only in Spain has the biretta continued to be worn without the raised ridges.

The use of the Roman biretta has been introduced by a certain number of the clergy into the Anglican Church. It is clear that there is no historical justification for this; for though both college cap and biretta are developed from the same "square cap," the biretta in its actual shape is strictly associated with the post-Reformation Roman Church, and its actual ceremonial use is of late growth. Braun (_Liturgische Gewandung_, p. 513) thinks that the symbolism of the cross may have had some influence in fixing and propagating the square shape, and he quotes a decree of the synod of Aix (1585) ordering the clergy to wear a biretta sewn in the form of a cross (_biretum in modum crucis consutum, ut ecclesiasticos homines decet_). So far as the legality of the use of the biretta in the Church of England is concerned, this was pronounced by Sir R. Phillimore in the Court of Arches (_Elphinstone_ v. _Purchas_, 1870) to be legal "as a protection to the head when needed," but this decision was reversed on appeal by the judicial committee of the privy council (_Hebbert_ v. _Purchas_, 1871). Of late years the old square cap of soft padded cloth or velvet has been revived in the Anglican Church by some dignitaries.

See J. Braun, S.J., _Die liturgische Gewandung_ (Freiburg-i-B., 1907); _Hierurgica Anglicana_, part ii. (London, 1903); H. Druitt, _Costume on Brasses_ (London, 1906). (W. A. P.)

BIRGER (?-1266), Swedish statesman, nephew of Birger Brosa, and the most famous member of the ancient noble family of the Folkungeaetten, which had so much to say for itself in early Swedish history, was created jarl of Bjaelbo by King Erik Eriksson in 1248 and married the king's sister. On Erik's death (1250) Birger's son Valdemar was elected king while his father acted as regent. During the sixteen years of his sway Sweden advanced greatly in fame and prosperity. In 1249 he led an expedition to Finland, built the fortress of Tavastehus, and thus laid the foundations of Sweden's oversea empire. He also built Stockholm, and enriched it by making it the chief mart for the trade of Luebeck, with which city he concluded a commercial treaty. As a lawgiver also Birger laboured strenuously in the interests of civilization. In his old age he married the daughter of King Abel. There is a fine statue of the great jarl in the Riddarholm church at Stockholm, erected by Fogelberg at the expense of the Stockholm magistracy in 1884. He is also the central figure of Fr. Hedberg's drama _Brollopet pa Ulfasa_ (1865).

See _Sveriges Historia_, vol. i. (Stockholm, 1879-1883).

BIRIBI, or CAVAGNOLE, a French game of chance, prohibited by law since 1837. It is played on a board on which the numbers 1 to 70 are marked. The players put their stakes on the numbers they wish to back. The banker is provided with a bag from which he draws a case containing a ticket, the tickets corresponding with the numbers on the board. The banker calls out the number, and the player who has backed it receives sixty-four times his stake; the other stakes go to the banker. In the French army "to be sent to Biribi" is a cant term for being sent to the disciplinary battalion in Algeria.

BIRJEND, the capital of Kain, a sub-province of Khorasan in Persia, in 32 deg. 53' N. 59 deg. 10' E., and at an elevation of 4550 ft. Pop. about 25,000. It is situated 328 m. from Meshed by the direct road, in a fertile valley running east and west, of which the southern boundary is a lofty range of barren hills known as Kuh i Bakeran. Through the valley runs the Khusp river, which loses itself in the desert towards the west; it is, however, generally dry. The water-supply of the town and of the 70 or 80 villages under its jurisdiction is very scanty. On the east of the town at the foot of a hill stands a dilapidated fort. Birjend has six good caravanserais, a college and some mosques; post and telegraph offices were established there in 1902.

BIRKBECK, GEORGE (1776-1841), English physician and philanthropist, was born at Settle in Yorkshire on the 10th of January 1776. He early evinced a strong predilection for scientific pursuits; and in 1799, after graduating as doctor of medicine, he was appointed to the chair of natural philosophy at the Andersonian Institution of Glasgow. In the following year he delivered, for the benefit of the working-classes, a gratuitous course of scientific lectures, which were continued during the two following years and proved eminently successful. He removed to London in 1804, and there he endeavoured to prosecute his philanthropic schemes, at first without much encouragement, but ultimately with marked success. In 1823 he contributed to found the Mechanics' Institute, the name of which was afterwards changed to Birkbeck Institution or College, in honour of its founder. He was appointed director of the institute, which he had originally endowed with the sum of L3700, and held the office till his death on the 1st of December 1841. The sphere of usefulness of the institution was gradually enlarged, and an enlargement of the buildings was carried out in 1883-1885. The college now holds day and evening classes in many of the sciences, in literature, languages and art.

BIRKENFELD, a town of Germany, capital of the principality of the same name, on the Zimmerbach, 25 m. S.E. of Trier and on the main line of railway from Bingerbrueck to Neunkirchen. Pop. 2500. Close by, on an eminence, lie the ruins of the castle of Birkenfeld, dating from the 14th century, once the residence of the counts palatine of Zweibruecken. The town has an Evangelical and a Roman Catholic church, a grand-ducal high school and a hospital. Besides brewing and tanning, its industries include the manufacture of tobacco and chicory. There is also a considerable trade in cattle.

The PRINCIPALITY OF BIRKENFELD is hilly and well-forested; agriculture prospers on the cleared lands, and fruit is grown in the valley of the Nahe, the principal stream. Ironstone and roofing slates are quarried, and there is some industry in agate-polishing and the manufacture of trinkets. The principality has an area of 312 sq. m. and a population (1900) of 43,409, chiefly Protestants. It is formed out of the former lordships of Dachstuhl and Oberstein, of part of the ancient countship of Sponheim, and sections of the duchy of Juelich, which were granted to the grand-duke of Oldenburg by the congress of Vienna in 1815. It is entirely an _enclave_ in Prussian territory, and though it is represented in the Oldenburg diet, it is governed by a separate _Regierungskollegium_, consisting of a president and two members, who are responsible to the Oldenburg ministry.

BIRKENHEAD, a municipal, county and parliamentary borough, and seaport of Cheshire, England, on the river Mersey, 195 m. N.W. of London. Pop. (1901) 110,915. It lies opposite Liverpool, on the east shore of the peninsula of Wirral, and is served by the Birkenhead (London & North-Western and Great Western joint) and the Wirral railways. It is wholly of modern growth, although the name of Byrkhed is traced to the forest which is believed to have extended between the mouths of the Dee and the Ribble in Lancashire. A Benedictine monastery was founded (c. 1150) by Hamon de Mascy, third baron of Dunham Massey, and dedicated to St Mary and St James. It drew its main revenues from tolls levied at the Mersey ferry; and its prior sat in the parliament of the earls of Chester, enjoying all the dignities and privileges of a Palatinate baron. A fine crypt, along with remains of the prior's lodging, refectory and chapel, may still be viewed, as the priory was purchased by private subscription and handed over to the municipality in 1896.

The rise of Birkenhead, from a hamlet of some 50 inhabitants in 1818 to its present importance, was due in the first place to the foresight and enterprise of William Laird, who purchased in 1824 a few acres of land on the banks of a marshy stream, known as Wallasey Pool, which flowed into the Mersey about 2 m. west of the village. Among other engineers, Telford and Stephenson favoured the project of converting Wallasey Pool into a great basin for shipping; but, largely owing to the fears of Liverpool lest a formidable rival should thus be created, it was not until 1843 that parliamentary powers were obtained, and the work entrusted to James Rendel, who finished it in less than five years. The docks, which covered an area of 7 acres, were opened in 1847, and after thrice changing hands were made over in 1858 to the Mersey Docks and Harbour Board, a body created by act of 1857, to control the harbourage on both sides of the river.

Meanwhile, the town itself grew rapidly. In 1833 an act was passed for paving, watching, cleansing and improving the streets; as well as for the regulation of police, and the establishment of a market. The Improvement Commissioners constituted by this act included the mayor, bailiffs and four aldermen of Liverpool, under whose care the main streets were laid out on a regular plan, intersecting one another at right angles; and the first iron tramway in England was laid down. Electricity was subsequently applied to the tramway system. Noteworthy public buildings are St Aidan's College, a large brick building in Tudor style, for the use of Anglican students in theology; the market hall (1843); town hall, a free library with branches, borough hospital, built at the cost of Sir John Laird; and many schools both public and private, including the industrial schools built as a memorial to Albert, prince consort, at the cost of Sir W. Jackson, and the school of art, given by Sir John Laird. There are many handsome modern churches, all built since 1821. Roman Catholics are especially numerous, owing to the presence of a large Irish population. The town is well furnished with open spaces. Birkenhead Park was opened in 1847, Mersey Park in 1885; while a tract of moorland 6 m. distant in the township of Thurstaston, was allotted to the borough of Birkenhead in 1887; and Meols Common, comprising over 50 acres of pastureland on the shores of Liverpool Bay, was made over to the corporation in 1900.

The increase of railway accommodation has been swift. In 1878 the old Monks Ferry station on the Great Western system was superseded by the opening of the Woodside passenger station, and a few years later the Birkenhead town station was opened. In 1886 the Mersey tunnel, connecting Birkenhead with Liverpool, was opened by the prince of Wales. The system extends from Rock Ferry and Park stations on the Cheshire side to the low-level at Central Station in Liverpool, and has connexions on the Cheshire side with the Great Western, North-Western, Wirral and various local lines. The Wrexham, Mold & Connah's Quay railway, which was taken over by the Great Central company in 1905, helped to bring the mineral wealth of Flint and North Wales generally into the Birkenhead docks.

Woodside Ferry may still be regarded as the principal entrance to Birkenhead and the Wirral from Liverpool. The exclusive right of ferryage was granted to the priory in 1332. In 1842 the Birkenhead Commissioners purchased it, under an act of parliament, from the lord of the manor, Mr F.R. Price. In 1897 the corporation further acquired the rights over the Rock Ferry and the New Ferry at the southern end of the town. Despite competition from the Mersey tunnel, these ferries continue to transport millions of passengers annually, and have a considerable share in the heavy goods traffic.

Though at the outset a mere commercial offshoot of Liverpool, Birkenhead has acquired a large export trade in coal and manufactured articles, importing guano, grain and cattle in return. Iron foundries, breweries, oil-cake and seed mills also exist side by side with such immense engineering and shipbuilding works as the Britannia Works, Canada Works, and, above all, Laird's shipbuilding works, where several early iron vessels were built, and many cruisers and battleships have been launched. Huge warehouses and sheds have been erected along the quays for the storage of freight. In 1847 the Birkenhead Dock Warehousing Company opened its first warehouse, capable of holding 80,000 tons of goods. A line called the Dock Extension railway was carried round the whole, and the company erected, for their workmen, the Dock Cottages. This entire property is now under the authority of the Mersey Docks and Harbour Board. The pile of buildings known as the corn warehouses are traversed by a canal which gives access to its several departments, and are provided with mechanical grain-elevators. There are also extensive lairages for live-stock, and cold storage for dead meat. On the north and north-east, and partly on the east, Birkenhead is bounded by its docks, which extend, for a distance exceeding 2 m., from the landing-stage at Woodside Ferry to the Wallasey Bridge. Of these the principal are the Egerton, Morpeth, Morpeth Branch and Wallasey Docks; while the Alfred Dock, with its three entrances, nineteen pairs of lock-gates, 8 acres of water, and 460 lin. yds. of quay-space, fulfils the part of an entrance-lock to the whole system. The great Float, now occupying the site of Wallasey Pool, separates Birkenhead from Poulton-cum-Seacombe in the parish of Wallasey. It forms an immense dock of 120 acres, with a quay-space of about 5 m.; and communicates on the E. with a low-water basin of about 14 acres and with the Alfred Dock; on the S.E. with the Morpeth, Morpeth Branch and Egerton Docks. The Morpeth Dock (about 11 acres, quay-space 1299 lin. yds.) is in communication with the Morpeth Branch Dock (about 31/2 acres, quay-space 600 lin. yds.); both being set apart for the use of steamers. The total water-space of these docks amounts to 165 acres, and the lineal quay-space is about 91/2