PART I (AVES).

A prodigious number of entozoa are known to infest birds. So far from birds being less victimised than mammals, the contrary is the case. Every now and then avian epizoötics, due to parasites, sweep off hundreds of these attractive hosts, and in some cases even nestlings are not secure from entozoal invasion. It might be supposed that predacious birds would be more liable to invasion than the graminivorous species. Such is not the case. The eagles, hawks, vultures, and owls certainly harbor a great variety of helminths, but as much may be said of the grain-feeding game birds, and still more of the water birds. Pheasants and land-fowl, grouse and partridges, are largely infested; whilst, of water-fowl, herons and plovers, rails and snipe, ducks and geese, cormorants and divers, gulls and awks, play the rôle of host to a practically infinite variety of parasitic guests. The presence of the worm-guests does not imply any previously diseased condition of the host. Shoot any water bird, say an oyster catcher (_Hæmatopus_), or, still better, a grebe (_Podiceps_), and then carefully examine its intestinal contents. You will probably find in its interior flukes and round worms, tapeworms and Echinorhynchi. Capture and examine a frog or a salamander. The result is the same, except that the cestodes would probably be absent. As for fishes, if entozoa be a proof of cachexia, then it follows that the normal condition of all piscine hosts is a diseased state. Examine any tolerably well-grown salmon, trout, pike, perch, roach, chub, carp, or barbel, and probably any one of them will contain at least three different kinds of parasites, each of which will be present in more or less considerable numbers. From what is stated above it would be obviously futile to attempt even an enumeration of the species of avian entozoa--a remark which applies almost equally to the other groups of hosts that remain for consideration. Confining our attention to a few of the more noteworthy facts, I may observe that we have no very trustworthy data respecting the power for mischief possessed by flukes. From what we know of their destructiveness in man and certain other mammals, it would be hazardous to pronounce them harmless. Scientifically, they furnish particulars of great interest. One of the most striking facts of recent study relates to Zeller’s discovery that the little cercariæ (_C. exfoliata_) which are contained in a peculiar sporocyst (_Leucochloridium paradoxum_), infesting the tentacles of a snail (_Succinea amphibia_), are in reality larval forms of a fluke (_Distoma macrostomum_) which resides in the intestinal canal of warblers (_Sylviadæ_). By experiment Dr Zeller reared the _Distoma_ in question in the intestines of whitethroats (_Curruca garrula_), in blackcaps (_C. atricapilla_), and in wagtails (_Motacilla_). Six days after transference the Cercariæ acquired sexual maturity. The odd thing is, that as the sporocystic _Leucochloridia_ resemble insect larvæ, they are attacked and swallowed by the birds under delusion. It is a curious example of mimetism in favour of the fluke’s welfare. To this and other equally brilliant scientific results helminthologists were gradually led up by the earlier researches of Steenstrup and Van Beneden. As remarked in my ‘Entozoa,’ ever since Steenstrup’s discovery of the fact that Cercariæ found in the bodies of water-snails were larval flukes, a peculiar interest has attached itself to this subject. Not only were the conclusions which he elicited novel in themselves, but they formed a basis for the enunciation of that interesting “law of alternate generation” with which the famous Danish naturalist’s name will ever remain associated. In all essential particulars Steenstrup’s statements have been verified.

By way of illustrating the phases of development through which the distomes pass I cannot do better than recapitulate in an abridged form the account I have previously given of _Distoma_ (_Echinostoma_) _militare_ of the snipe and curlew. This account is based on the investigations of Van Beneden, Von Siebold, and Pagenstecher. I regret that it is out of my power to reproduce the illustrations that have already appeared on this head in my introductory treatise (see ‘Entozoa,’ figs. 5 to 9 inclusive). Our _Echinostoma militare_ produces oval-shaped eggs, which give birth to a free ciliated embryo, and this embryo produces a sporocyst or scolex by internal budding. When the sporocyst separates itself from the embryo it presents a very simple appearance, but showing already a cæcal digestive tube. The tail end is fissured, indicating an early stage of formation of caudal appendages. In the next stage we have a well-developed head and body, the tail becoming strongly pronounced. Limb-like caudal lobes project on either side, and an oral sucker makes its appearance in front. This sucker communicates with the œsophageal bulb and passes directly into the digestive cæcum, which contains a variable number of rounded particles. At this stage, also, incompletely developed Cercariæ may be seen in the perivisceral cavity. These Cercariæ are at first shapeless organisms, but after passing through a series of gradations they ultimately assume a definite form, which, in many cases, is sufficiently distinctive to enable us to refer the Cercariæ to particular species of _Distoma_. The older writers regarded many of the cercarians as adult flukes. In the early state these larvæ are furnished with tails. They may be seen lodged within the cavity of the body of the sporocysts, being twisted and folded in various attitudes. The Cercariæ not only exhibit a cephalic and ventral sucker, but also a dark forked line representing the digestive system. At a still further stage other structures come into view, until the perfect Cercaria displays an oral sucker, a pharyngeal bulb, an œsophagus, two alimentary cæca, a ventral sucker, a water-vascular system consisting of two main excretory ducts, and a contractile vesicle, by means of which the ducts communicate with the external surface. The tail is conspicuous and furnished with a fringe. The alimentary organs conform to the general trematode type, but before passing into the sexually-mature condition other changes are undergone. The Cercariæ part with their tails, and subsequently they encyst themselves on or within the surface of the body of some mollusk. Their pupa condition is thus arrived at. The pupa itself differs from the cercaria in presenting a double crown of hooks surrounding the head, but the other organs correspond with those already described. According to Van Beneden the hooks make their appearance immediately after encystation. In this condition it is next transferred to the intestine of some higher animal, and in this final situation it gradually acquires all those organs the possession of which will entitle it to be called a sexually-mature or adult distome. In the immature fluke we may now discern the mouth, the buccal or cephalic sucker, the pharyngeal bulb, the œsophagus, the digestive cæca, the coronal spines, the contractile vesicle, the aquiferous system of vessels, the matrices of the yelk-forming glands, and also a central mass of cellules, from which all the other reproductive organs will in due time be developed. In the adult _Echinostoma militare_ the upper third of the body is clothed with little spines. Taking this example as illustrative of the ordinary mode of fluke development we find that a change of hosts is necessary, and that in the intermediate state they occupy the bodies of mollusks. Thus, for the continuation of the species, there must needs be a contemporaneity of vertebrate and evertebrate hosts. Surely no reasonable person can ascribe this concurrence to merely fortuitous circumstances. In this connection I may remark that Villot, in his account of the migrations of the trematodes, states that the cercarian forms of _Distoma leptosomum_ and _D. brachysomum_ of _Tringa alpina_ occur in _Scrobicularia_ and _Anthura_. These parasites are also found encysted in the gizzard of _Tringa_.

The tapeworms of birds are undoubtedly injurious to their bearers. All the worms appear to be armed with cephalic hooks; at least, such is the case with the species described by Krabbe, who has supplied figures of the hooks drawn to a scale. Dr Krabbe’s beautiful monograph is a perfect model of its kind. In the accompanying figure the hooks have fallen (Fig. 72). On account of the frequency of their occurrence, some persons have supposed that tapeworms are not injurious to their hosts, forgetting that it is not the mere fact of the existence of tapeworms, but their excessive numbers during particular seasons that give rise to avian epizoötics. The same rule holds good with other parasites. Of course, in fledgelings, as also obtains in yearlings amongst our domesticated animals, a very few parasites are sufficient to prove destructive to the bearer. Thus, as regards the so-called “grouse-disease,” during one season it may be due to tapeworms, during another to strongyles, during a third to excessive abundance of both these parasites. Unfortunately, other avian epizoötics, not necessarily due to parasites of any kind, may be mistaken for helminthic epizoöty. The same thing happens amongst quadrupeds. We have, for example, parasitic equine epizoötic outbreaks, and likewise non-helminthic equine epidemics (as in the case of the Egyptian horse plague of 1876). The true nature of any epizoöty can only be determined by competent investigation. That was well shown in the grouse epidemic of 1872. In that epizoöty the greater number of the birds succumbed to the injuries produced by a nematode worm (_Strongylus pergracilis_, Fig. 73), but, without doubt, the occasional presence of numerous tapeworms (_Tænia calva_) hastened the consequent fatality. The following table, giving the results of examination of twelve diseased grouse from the Earl of Cawdor’s estate, will show how inconspicuous a part tapeworms played in the epidemic of 1872. For further details I must refer to my brochure on the ‘Grouse Disease,’ and to some other memoirs quoted in the bibliography below.

+----------+-----------+---------------+-----------+----------------+ | No. of | Condition | State of | Tapeworms | Strongyles | | specimen.| of bird. | viscera. | present. | present. | +----------+-----------+---------------+-----------+----------------+ | 1 | Good | Full | None | Abundant. | | 2 | Emaciated | Putrid | Two | Very numerous. | | 3 | Good | Full | None | Abundant. | | 4 | " | " | " | " | | 5 | " | " | One | " | | 6 | " | Shrunken | Two | Very numerous. | | 7 | Emaciated | Much shrunken | None | " | | 8 | Thin | Shrunken | " | " | | 9 | " | " | " | " | | 10 | Emaciated | Distended | Man | " | | 11 | Thin | Rather full | Several | Abundant. | | 12 | " | " | None | Very numerous. | +----------+-----------+---------------+-----------+----------------+

I have said that tapeworms prove fatal to young birds, even to nestlings. A notable instance of this is recorded by Mr Eames. The parasites were examples of _Tænia angulata_. Apart from the epidemiological aspects of the subject, it is not uninstructive to notice the variety of helminths that infest the common fowl and game birds. Accordingly, I append a similar but more extended list than that previously given in the supplement to my introductory treatise:

Key to Column Headings:

A = Common fowl. E = Red Grouse. B = Pheasant. F = Grey Partridge. C = Capercaillie. G = Red Partridge. D = Black Grouse. H = Quail.

+----------------------------------+---+---+---+---+---+---+---+---+ | Entozoa of game birds and the | A | B | C | D | E | F | G | H | | common fowl. | | | | | | | | | +----------------------------------+---+---+---+---+---+---+---+---+ |_Monostoma verrucosum_, Zeder | * | | | | | | | | |_Distoma oxycephalum_, Rudolphi | * | | | | | | | | | " _ovatum_, Rudolphi | * | | | | | | | | | " _lineare_, Zeder | * | | | | | | | | | " _dilatatum_, Miram | * | | | | | | | | | " _fuscatum_, Rudolphi | | | | | | | | * | |_Filaria Mansoni_, Cobbold | * | | | | | | | | |_Ascaris vesicularis_, Froelich | * | * | * | | * | * | | * | | " _gibbosa_, Rudolphi | * | | | | | | | | | " _inflexa_, Rudolphi | * | | * | | | | | | | " _compar_, Schrank | | | | * | * | * | | * | |_Spiroptera hamulosa_, Diesing | * | | | | | | | | | " _helicina_, Molin | | | | | | | * | | |_Dispharagus nasutus_, Dujardin | * | | | | | | | | | " _spiralis_, Molin | * | | | | | | | | |_Strongylus pergracilis_, Cobbold | | | | | * | | | | |_Sclerostoma syngamus_, Diesing | * | * | | | | * | | | |_Trichosoma longicolle_, Rudolphi | | * | * | * | | * | | | |_Tænia malleus_, Goeze | * | | | | | | | | | " _microps_, Diesing | | | * | * | | | | | | " _exilis_, Dujardin | * | | | | | | | | | " _calva_, Baird | | | | | * | | | | | " _linea_, Goeze | | | | | * | * | | * | | " _infundibuliformis_, Goeze | * | * | | | | | | | |_Ligula reptans_, Diesing | | | * | | | | | | +----------------------------------+---+---+---+---+---+---+---+---+

In regard to this list I can only afford space to remark that several of the species are possibly mere varieties. Some of the worms are of great interest. It occasionally happens that _Distoma ovatum_ is found in the albumen of the fowl’s egg, and it is even more common to obtain _Ascaris inflexa_ from the same situation. For a recent example I am indebted to Dr Walker, of Peterborough. _Spiroptera helicina_ resides in the feet, occasioning enlargement of the joints and consequent distress to the bearer. Probably the most important in the list is my _Strongylus pergracilis_. Here I may mention that on the 10th of April, 1878, I received a letter from Dr Manson, of Amoy, announcing his acquaintance with a filaria infesting the eye of the fowl. On the 9th of May I also received from Dr Manson the head of a bird showing examples of the worm. As the species is new to science I have proposed to call it _Filaria Mansoni_, after the discoverer. The male is 5/8″ and the female 3/4″ in length. Of the injurious nematodes, giving rise to avian epizoöty, probably one of the most destructive is _Ascaris maculosa_ infesting pigeons. On the 9th of October, 1873, I received a letter from Dr J. Alexander Macdonald, of Woburn, Bedfordshire, stating that he had forwarded to me a pigeon which had been found dead on the previous morning. It seems that the owner of the bird had erected a large pigeon-house, and had imported a number of Antwerp smerles, these birds all continuing in a perfect state of health until about a week before the above-mentioned date, when, to use Dr Macdonald’s words “first one and then another was attacked, and so on, until four or five of the pigeons had died after a few hours’ illness.” The suddenness of these attacks not unnaturally suggested poisoning; and, accordingly, says my informant, the owner “had the curiosity to open one of the birds, when, to his astonishment, he found the intestines stuffed with worms.” Two days later I received a letter from Dr Macdonald, stating that several others of the flock had died, and it further appeared to him probable that the daily list of sick and dying would continue to increase. On the 14th of the month three more of the birds were dead. On the 4th of the following November, the same correspondent obligingly informed me that the epidemic had been “at last mastered.” It seems that altogether twelve birds had perished. On the 9th of October one of the birds was carefully examined by me, and the results were so interesting that I am constrained to give a few of the particulars originally communicated to the Zoological Society. As stated in my paper, the whole intestinal tract of the dead bird was crowded with these ascarides. The small intestine was inflamed throughout, and showed several large ulcerated patches; nevertheless, there were no traces of emaciation. From this it was evident that the parasites had grown quickly, the malady having a correspondingly rapid formation. The distribution of the parasites was curious. One specimen, two inches long, reached from the crop to the proventriculus. The cavities of this organ and of the gizzard were crammed with worms completely blocking the passage. Three of the worms had also placed themselves within the pyloric opening, their bodies partly lodging within the duodenum. The duodenum itself was crowded with worms, their numbers somewhat decreasing downwards. I removed thirty-six worms from the œsophagus, proventriculus, and stomach, besides 166 others from the intestinal canal, thus obtaining a total of no less than 202 nematodes from this small host. Considering the large size of these entozoa, the extent of infection must be pronounced remarkable. The largest females measured 2-1/2″ in length. One of the most interesting facts--serving to exemplify a well-known habit of lumbricoid worms generally--consisted in the circumstance that two of the parasites had succeeded in perforating the horny lining membrane of the gizzard. The injuries had been accomplished during the life of the host, for the walls of the gizzard were inflamed opposite the perforations. There was a little half digested food within the stomach, the _débris_ of which, when placed under the microscope, showed several ova. There were no free embryos, neither had the development of the freed eggs proceeded beyond yelk-segmentation. Free eggs were also found both in the small and large intestine. The eggs measured about 1/360″ by 1/700″ in diameter. Referring to my paper for further anatomical details, I can only add that, despite these facts, the ascarides in question do not appear to be a very frequent source of epizoöty. It was remarked by Dujardin that Heister, at Rostok, and Gebauer, at Breslau, found this parasite abundant at the beginning of the eighteenth century; but, according to examinations conducted at Vienna, the worm was found in the common pigeon in only eleven instances out of 245, and thrice only in thirty-eight examples of the ring-dove; moreover, the examination of eighty-seven other pigeons and doves of different species yielded entirely negative results. The Dublin helminthologist, Bellingham, noticed the occurrence of this parasite in Ireland.

Any attempt so much as to enumerate the species of nematoids infesting birds would carry me far beyond the aim and scope of this treatise. One of the commonest species is _Ascaris (Heterakis) vesicularis_. Many hundreds of forms have been described by Dujardin, Diesing, Molin, Krabbe, and other systematists, and it remains for some future laborer to condense the facts which are dispersed throughout a very wide-spread literature. As regards the particular species of nematoids that are either actually known or conjectured to be injurious to birds I can only find space to repeat some of the particulars which I have elsewhere recorded in respect of _Sclerostoma syngamus_. In 1799 a letter from Dr Wiesenthal, of Baltimore, U.S., was published in the ‘Medical and Physical Journal,’ containing an account of a parasite infesting the trachea of fowls and turkeys in America. The communication is dated May 21st, 1797, and is the first public record concerning the entozoon. Dr Wiesenthal says: “There is a disease prevalent among the gallinaceous poultry in this country, called the _gapes_, which destroys eight-tenths of our fowls in many parts, and takes place in the greatest degree among the young turkeys and chickens bred upon old-established farms. Chicks and poults, in a few days after they are hatched, are found frequently to open their mouths wide and gasp for breath, at the same time frequently sneezing and attempting to swallow. At first the affection is slight, but gradually becomes more and more oppressive, and it ultimately destroys. Very few recover; they languish, grow dispirited, droop, and die. It is generally known that these symptoms are occasioned by worms in the trachea. I have seen the whole [windpipe] completely filled with these worms, and have been astonished at the animals being capable of respiration under such circumstances.”

Any one who has witnessed the _gapes_ will at once recognise the accuracy of Wiesenthal’s description; and so far as the phenomena of the disease are concerned, very little more has been added in the numerous accounts which have since appeared. On the 1st of August, 1808, the English naturalist, George Montagu, communicated to the Wernerian Society a paper entitled “Account of a species of _Fasciola_ which infests the trachea of poultry, with a mode of cure.” Montagu does not appear to have been aware of the existence of any previous record. He gave a scientific description of the parasite, which led to its being noticed in the systematic works of Rudolphi, Dujardin, and Diesing, but the best accounts of the worm are due to Von Siebold. _Sclerostoma syngamus_ has been found in the trachea of the turkey, domestic cock, pheasant, partridge, black stork, magpie, hooded crow, green woodpecker, starling, and swift. In July, 1860, I obtained a fowl suffering from the gapes, and operated upon it in the following manner:--A small portion of wool having been dipped in chloroform and placed in front of the nostrils the bird soon became insensible. The skin of the neck was then divided and the trachea slit up to the extent of a quarter of an inch. With a pair of common dissecting forceps, I removed seven Sclerostomata. Six of these parasites were sexually united, the odd worm being a female. After I had closed the external wound with a single thread the bird woke out of its artificial sleep, when it soon recovered its legs, and ran about the table vigorously. Moreover, in a very few minutes it devoured the contents of a saucer partly filled with bread and milk. An occasional gape was caused by an accumulation of frothy mucus within the injured trachea, but this obstruction the bird soon got rid of by shakes of the head and sneezing. The only subsequent inconvenience to the bird arose from emphysematous distension of the cellular tissue of the head and neck. This was relieved by puncture, the emphysema ceasing to form after the external wound had healed. Some months afterwards I destroyed the bird, and on dissecting the neck, a distinct cicatrix was found indicating the site of the operation on the trachea. The divided cartilaginous rings, six in number, were united only by a thin layer of connective tissue. The female worms gave an average length of 5/8″, the males scarcely exceeding 1/3″. The mouth is furnished with six prominent chitinous lips. In both sexes the surface of the body is quite smooth, but the tail of the female exhibits a tendency to fold upon itself. The lower part of the body suddenly contracts to form a short, narrow, mucronate, pointed tail. The male is usually found rigidly affixed by means of a strong, membranous, sucker-like bursa, which proceeds from the lower end of its body. In regard to the peculiar mode of union of the sexes, it becomes an interesting point to ascertain whether there be an actual incorporation of the substance of the copulatory organs during or after the act of impregnation. In my specimens none of the three pairs were organically united, and I succeeded in separating one pair very readily. Dujardin speaks of them as being soldered together, whilst the statements of Von Siebold are still more explicit. In connection with this subject the latter observer makes the following comment (‘Wiegmann’s Archiv,’ 1836, s. 106):--“The two sexes of almost all round worms are united only at the time of copulation. The male of _Heteroura androphora_ has also the habit of remaining connected with its mate beyond the period of copulation; here, thus, there is a continuous union of the sexes without a growing together; and in _Syngamus trachealis_ there is ultimately a lasting continuity of the sexes by means of an actual growing together.” Having confidence in Von Siebold’s statement, I concluded that the sexual union in my specimens had only recently been effected. Admitting this to have been the case, one naturally asks how the mature eggs can make their escape. Clearly, the eggs can only escape by an eventual breaking up of the body of the parent. The eggs of _Sclerostoma syngamus_ are comparatively large, measuring 1/250″ in length. Many of the ova contained fully formed embryos, and in the centre of the lower third of the body of one of them I perceived an undulating, imperfectly formed intestinal tube. By whatever mode the young escape the shell, it is clear that they are already sufficiently developed to undertake an active migration. A change of hosts is probably necessary, but in the first instance they either enter the substance of fungi or other vegetable matters, or they bury themselves in the soil at a short distance from the surface. In view of checking the destructive influences of this parasite, the following methods have been recommended.

_First._ The simplest plan consists, as Dr Wiesenthal long ago pointed out, in stripping a feather from the tube to near the narrow end of the shaft, leaving only a few uninjured webs at the tip. The bird being secured, the webbed extremity of the feather is introduced into the windpipe. It is then twisted round a few times and withdrawn, when the worms are found attached. In some instances this plan succeeds entirely.

_Secondly._ The above method is rendered more effectual when the feather is previously steeped in some medicated solution which will destroy the worms. Mr Bartlett employs salt for this purpose, or a weak infusion of tobacco; and he informs me that the simple application of turpentine to the throat externally is sufficient to kill the worms. It should be borne in mind that the bird itself may be injuriously affected by these drugs if they are carelessly employed.

_Thirdly._ The treatment recommended by Mr Montagu proved successful in his hands, although the infested birds were old partridges. One of his birds had died of suffocation; but he tells us that “change of food and change of place, together with the infusion of rue and garlic, instead of plain water, to drink, and chiefly hemp-seed, independent of the green vegetables which the grass plot of the menagerie afforded, recovered the others in a very short time.”

_Fourthly._ The plan I employed in my experiment. This is only desirable in advanced cases, where suffocation is impending. It will afford instant relief, as the trachea may be cleared of all parasitic obstructions.

_Lastly._ The essential point to be observed is the total destruction of the worms. This will help to put a stop to future epizoöties. If the parasites are merely killed and thrown away carelessly, the eggs will sustain no injury. Decomposition having set in, the young embryos will sooner or later escape their shells, migrate in the soil or elsewhere, and ultimately find their way into the air-passages of birds in the same manner as their parents did before them.

In this place I must not omit to mention the remarkable circumstance, quoted in my pamphlet on the grouse disease, that Prof. Wyman, of Boston, found _Eustrongyli_ surrounding the cerebellum in seventeen out of nineteen snake-birds or water-turkeys that had been shot in Florida. These viviparous nematodes apparently occasion their avian bearers no inconvenience. No doubt, as Wyman observes, their presence must be regarded as a normal state of things: but should they occur in excessive numbers, then we can hardly doubt the result.

As regards acanthocephalous parasites, although not so numerous as the nematodes, it is extremely probable that they play a similar rôle. Parasites which prove fatal to swine are scarcely likely to be harmless in birds. On the 18th of February, 1875, I received from Sir Joseph Hooker eleven worms for identification. Mr Charles P. Hooker, his son, subsequently informed me by letter that he had found them in a Redwing (_Turdus iliacus_) which he dissected in January, 1875. The worms (_Echinorhynchus transversus_) occupied the large intestine, probably to the number of one hundred in all. Hitherto this parasite has been found abundantly in the blackbird, thrush, and in most of the _Turdidæ_; but not in the redwing. It has also been obtained from the starling and red-breast. The presence of so many of these armed parasites in one small host could hardly fail to inflict severe injury on the bearer.

In concluding this section of my work I can only find space to make a few acknowledgments. Most of the rare, new, or interesting avian entozoa which I have examined and described have been received either from the Zoological Gardens, or from personal friends. In particular I may mention the collections sent to me by Mr Charles Darwin, Mr Robert Swinhoe, Mr Charles W. Devis, Dr Murie, Dr John Anderson, and Mr Spooner Hart, of Calcutta. A great many correspondents have contributed single specimens, many of which I have already incidentally acknowledged in these pages. In this place I must particularise the new species (_Ascaris Cornelyi_) which I described from specimens sent to Mr Sclater. This worm infests the vulturine pintado (_Numida vulturina_). Mr Darwin’s collection contained fine examples of _Filaria horrida_ from the American ostrich (_Rhea_). When dissecting birds at the Zoological Society’s Menagerie, I obtained (in addition to the parasites already mentioned) _Distoma æquale_ from the American owl (_Strix perlata_); _Tænia multiformis_ from the night heron (_Ardea nyctocorax_); _T. infundibuliformis_ from a horned pheasant (_Phasianus_); _T. lævis_ and _T. lanceolata_ and also _Ascaris tribothrioides_ from a dusky duck (_Anas obscura_); _Eustrongylus papillosus_ (fig. 75) from the larus crane (_Grus antigone_); _Trichosoma longicolle_ from the horned pheasant, and _T. brevicolle_ from the Sandwich Island goose (_Bernicla Sandwichensis_). This bird was also infested by _Spiroptera crassicauda_ and _Ascaris dispar_. From the ring-necked pheasant (_Ph. torquatus_) and from the black-backed Kaleege (_Euplocomus melanotus_), and also from a cheer pheasant (_Ph. Wallichii_), I obtained abundance of _Ascaris vesicularis_. From the ashy-headed goose (_Chloephaga poliocephala_) examples of _Str. tubifex_ and _Str. nodularis_. This bird also yielded a new species (_Str. acuticaudatus_). From a tinamou (_Tinamus_) I obtained the _Ascaris strongylina_ of Rudolphi (_Str. spiculatus_, mihi). From amongst our British birds I have obtained _Asc. depressa_, _Trichosoma falconum_ and _Hemistoma spathulum_, from the kite (_Falco milvus_). Of these three worms, the last named was also found in the long-eared owl (_Strix otus_), whilst the first likewise occurred in a kestrel (_Falco tinnunculus_) and in a honey buzzard (_Pernis apivorus_). I may add _Filaria attenuata_ from a peregrine (_F. peregrinus_); and _F. leptoptera_ from a sparrow hawk (_Accipiter nisus_). From the redshank (_Totanus calidris_) I obtained _Tænia variabilis_, and from the curlew (_Numenius arcuata_) _T. sphærophora_; and from various gulls (_Larus glaucus_ and _L. tridactylus_) the _Tetrabothrium cylindraceum_. Also from the grey gull _Echinostoma spinulosum_. From the red-throated diver I procured _Tetr. macrocephalum_. I found this tapeworm also in the guillemot (_Uria troile_), together with a nematode (_Ascaris spiculigera_) two examples of which were lodged in the right auricle of the heart. From a capercaillie (_Tetrao urogallus_) I have obtained a species of _Ligula_, and likewise numerous examples of _Trichosoma longicolle_. Of necessity, this brief notice only comprises a small part of the avian entozoa contained in my collection, many of which I have not had time to describe, whilst, as regards others, I can only say that they remain in abeyance for examination and identification.

Mr Brotherston has recently recorded an interesting find (made Nov. 25th, 1874) of nematodes in the legs of the lesser grebe (_Podiceps minor_), and also (Feb. 27th, 1878) in the waterhen (_Gallinula chloropus_). Both limbs of both birds were infested. The worms of the grebe were spirally coiled amongst the muscles and tendons near the lower end of the tibia, and when unrolled measured about an inch in length. The parasites of the waterhen were similar in appearance. Not improbably these were all sexually-imperfect female examples of _Filaria acuta_ hitherto found in the abdomen of grebes.

The British Museum contains many interesting specimens purchased from the collection of Von Siebold, but they are practically inaccessible to investigators. The entozoa in the Hunterian Collection, though few in number, are in an excellent state of preservation, and at all times accessible to visitors.

The ectozoa of birds are too numerous to be dealt with in these pages. References to recent papers by Haller, Mégnin, and Westwood will be found below. The insects infesting the domestic fowl have been alluded to in connection with the occurrence of poultry-lousiness in the horse.

BIBLIOGRAPHY (No. 57).--(Anonymous), “On the (gape) Diseases of Fowls,” the ‘Veterinarian,’ p. 267, 1841.--(Anon., initialed “Q.”), Letter on the “Grouse Disease,” in the ‘Times,’ Sept. 5, 1874.--(Anon.), “On Grouse and Partridge Disease,” being annotations in the ‘Lancet,’ Sept. 4, 1875, pp. 360 and 361.--(Anon.), “Grouse Disease,” letter signed “R.” (probably from Lord Ravensworth), in ‘Land and Water,’ Aug. 16, 1873.--(Anon.), “Grouse Disease,” article (from “W. C.”) in the ‘Field,’ Aug. 2, 1873 (criticising my brochure.--T. S. C.).--_Arlong_, “Note on Tænia from the Fowl,” ‘Rec. Méd. Vét.,’ 1875.--_Baird, W._, “Descr. of _Tænia calva_ from the Grouse,” in ‘Brit. Mus. Catalogue,’ p. 83.--_Blavette_, “Descr. of a Verminous Disease among Fowls,” ‘Veterinarian,’ p. 649, 1840.--_Brotherston, A._, “Parasitic Worms in Legs of Grebe (_Podiceps minor_) and Water-hen (_Gallinula chloropus_),” ‘Science Gossip’ for April, 1878, p. 88, and in ‘Proceedings of the Berwickshire Naturalists’ Club,’ vol. viii, p. 288.--Carter, B. (see Cobbold).--_Chapman, H. C._, “Description of a new Tapeworm from Rhea,” ‘Proceed. Phil. Acad.,’ 1876, p. 14.--_Chatin, J._, “Étude sur des helminthes nouveaux ou peu connus (treating of a Cyathostoma, from _Anas tadorna_ and _Sclerostoma pelecani_),” ‘Annales des Sciences Naturelles,’ 1875.--_Cobbold_, ‘The Grouse Disease, a statement of facts tending to prove the Parasitic Origin of the Epidemic,’ London, 1874.--_Idem_, Letter in the ‘Field,’ Sept. 9, 1872.--_Idem_, “Contributions to our Knowledge of the Grouse Disease, with description of a new Species of Entozoon,” ‘Veterinarian,’ March, 1873; see also an article (by Brudenell Carter) in the ‘Times’ for Sept. 5, 1874; repr. in the ‘Veter.,’ Oct., 1874.--_Idem_, “Remarks on the Entozoa of the Common Fowl and of Game-birds, especially in relation to the Grouse Disease,” the ‘Field,’ Sept. 14, 1867, and ‘Brit. Assoc. Rep.,’ 1867.--_Idem_, “On Sclerostoma and the Disease it occasions in Birds,” ‘Linn. Soc. Proc.,’ 1861; repr. in the ‘Field,’ June 22, 1861, and in ‘Edin. Vet. Rev.,’ vol. iii, p. 439, 1861, also in Tegetmeier’s work on ‘Poultry;’ see also a comment on “Gapes,” by “Umbra,” in the ‘Field,’ June 29, 1861.--_Idem_, “Parasites from the Zoological Gardens,” ‘Intellectual Observer,’ 1862.--_Idem_., “Notes on Entozoa (species Nos. 1, 7, 9, 12),” in ‘Zool. Soc. Proc.,’ 1873-76.--_Idem_, ‘Linn. Soc. Trans.,’ 1858.--_Idem_, “On Entozoa of Birds and Fishes, collected by Mr Charles W. Devis,” ‘Zool. Soc. Proc.,’ 1865.--_Idem_, “Note on Entozoa in the Crested Grebe,” the ‘Field,’ March 29, 1873.--_Colquhoun, W._, ‘Remarks on the decrease of Grouse, and on the Grouse Disease (Gapes),’ Edinburgh, 1858; see also a notice in ‘Edin. Vet. Rev.,’ vol. i, April, 1859.--_Crisp, E._, “Note on Hydatids in an old Honduras Turkey,” ‘Path. Soc. Trans.,’ 1863.--_Idem_, “On Sclerostoma,” ‘Rep. of Path. Soc.,’ in ‘Med. Times and Gaz.,’ Oct. 26, 1876, p. 474.--_Idem_, “Note on Filaria in the Heart of a Peregrine Falcon,” ‘Path. Soc. Trans.,’ 1854.--_Davaine_, ‘Syngame de la trachée,’ p. 37, and ‘Synops.’ cxiv, in his ‘Traité.’--_Devis, C. W._ (see Cobbold).--_Diesing_, ‘Revis. der Myzelminthen,’ Abtheil. “Trémat.,” 1858.--_Idem_, “Tapeworm from Podiceps,” in his ‘Zwanzig Arten von Cephalocotyleen,’ Wien, 1856.--_Idem_, see various species in his ‘Revisionen,’ given in Bibl. No. 58.--_Eames, C. J. L._, “On Tapeworm in Blackbirds,” letter to the ‘Lancet,’ June 9, 1877, p. 863.--_Farquharson, R._, “The Grouse Disease (due to a contagious fever),” letter to the ‘Lancet,’ Sept., 1874.--_Fergusson, J._, “On Grouse Disease,” letter in the ‘Times,’ July 16, 1878.--_Gentles, T. W._, “Tapeworm in Birds,” letter to the ‘Lancet,’ Jan. 18, 1868, p. 106.--_Haller, G._, “Freyana und Picobia, zwei neue Milbengattungen,” in ‘Sieb. u. Köll. Zeitsch.,’ 1877, s. 181.--_Johnston, D._, “On the Grouse Disease,” letter in the ‘Lancet,’ Sept. 20, 1873, p. 441.--_Krabbe_, ‘Bidrag til Kundskab om Fuglenes Bændelorme,’ Copenhagen, 1869 (contains a summary in French, ‘Recherches sur les Ténias des Oiseaux’).--_Linstow, O. von_, “Euthelminthologica” (containing descriptions and notes on worms from birds, fishes, reptiles, and mollusks), ‘Archiv für Naturgeschichte,’ 1877.--_Idem_, “New Flukes (_Dist. vitellatum_ and _D. macrophallus_) from _Totanus hypoleucus_, and _D. cælebs_ from Fringilla,” Beobacht. in ‘Arch. f. Naturg.,’ 1875, s. 189-193.--_Maclagan_, “Note on the Grouse Disease,” ‘Proc. Roy. Soc. of Edin.,’ April 20, 1874, p. 378.--_Marion_, “Révis. des Némat. du Golfe de Marseilles,” ‘Compt. Rendus,’ 1875.--_Mégnin, P._, “On Harpirhynchus and other Mites,” in ‘Rev. f. Thierheilk.,’ Oct., 1878, s. 146.--_Idem_, “Mémoire sur les Cheylétides Parasites (Picobia, &c.),” ‘Journ. d’Anat. et de Physiol.,’ 1878; see also ‘Rev. f. Thierheilk.,’ Sept., 1878 _et seq._--_Molin_, in his various monographs (quoted in Bibl. Nos. 54, 56, and elsewhere).--_Montagu, G._, “Account of a species of Fasciola which infests the Trachea of Poultry, with a mode of Cure,” ‘Memoirs of the Wernerian Nat. Hist. Soc.,’ vol. i, p. 194, 1811.--_Perrier_, ‘On Syngamus’ (brochure, Paris, 1875).--_Pulteney, R._, “On Ascarides discovered in _Pelicanus carbo_ and _P. cristatus_,” ‘Linn. Trans.,’ vol. v, 1800, p. 24.--_Röll_, “Beitrag. zur Entwickelungsgeschichte der Tænien,” ‘Verh. d. Würzb. p. m. Ges.,’ Bd. iii, 1852, s. 51.--_Sanderson, J. B._, “On Grouse Disease,” ‘Brit. Med. Journ.,’ May 15, 1875.--_Small, M._, “Worms in the Eyes of Geese,” from the ‘Irish Farmer’s Gaz.,’ in the ‘Veterinarian,’ 1862, p. 19.--_Tait, L._, “Tapeworm in Birds,” letters to the ‘Lancet’ for Jan. 25, 1868, p. 145, and Feb. 8, 1868, p. 214; see also “Pediculus,” _ibid._, p. 180.--_Tegetmeier_, “On the Grouse Disease,” in the ‘Field,’ Sept. 12, 1874.--_Thick_, “Letter on the Cure of Gapes,” in ‘Land and Water,’ Aug., 1867, p. 77.--_Vaughan_, “The Grouse Disease,” in the ‘Field,’ Aug. 23, 1873.--_Villow, A._, “Sur les migrations, et les Métamorphoses des Trematodes,” ‘Comptes Rendus,’ 1875, and ‘Ann. Nat. Hist.,’ 1875 (chiefly on flukes of the sea-lark, _Tringa alpina_).--_Idem_, “Sur le syst. nerveau,” &c., _ibid._, 1875.--_Idem_, “On the Helm. Fauna of the Coast of Brittany (chiefly from birds),” ‘Ann. Nat. Hist.,’ from ‘Comp. Rend.,’ 1875, p. 1098, and from ‘Arch. de Zool. Expérim. et gén.,’ 1875.--_Idem_, “Sur l’appareil des Trematodes (_Dist. insigne_),” ‘Compt. Rend.,’ 1875.--_Wedl, K._, ‘Anatomische Beobachtungen ueber Trematoden,’ Wien, 1858 (contains excellent descriptions of numerous flukes, chiefly from birds).--_Westwood, J. O._, “New Flea on a Fowl (Sarcopsillus),” ‘Entom. Month. Mag.,’ xi, p. 246, 1875.--_Wiesenthal, A._, “Account of a Parasite infesting the Trachea of Fowls and Turkeys in America,” ‘Med. and Phys. Journ.,’ vol. ii, p. 204, 1799.--_Wyman_, “On Eustrongyli within the Cranium of Water-Turkeys,” ‘Proc. Boston Nat. Hist. Soc.,’ 1868.--_Youatt_, “On a Verminous Disease in Poultry” (being a letter to him), ‘Veterinarian,’ p. 648, 1840.--_Zeller_, “On Leucochloridium,” from ‘Zeitsch. f. wissensch. Zool.,’ 1874, s. 564, and from ‘Bibl. Univ. Bullet. Sci.,’ 1874, p. 366, in ‘Ann. Nat. Hist.,’ Feb., 1875.