part I call the pulley is merely an upper sinus of the large orifice

that receives the pedicle of the abdomen. The shape of these orifices, both of the trunk and abdomen, varies in different genera: thus, in the bee it is triangular, with the vertex reversed; and in the wasp the upper one is circular, and the lower one transversely oblong; but in all, the apertures of the trunk correspond with those of the abdomen. In _Evania_, in which the minute abdomen is inserted in the upper side of the metathorax, there is scarcely any trace of this structure. With regard to the articulation of the pedicle itself with the lower orifice of the trunk, it appears simply suspended, with little or no inosculation. I may observe under this head, that though the abdomen in almost all insects is wholly clear of the cavity of the trunk, yet in some _Phalangidæ_ (_Gonyleptes_ K.) it appears almost retracted within it[2130].

iii. _Composition._ I shall next consider the _segments_ into which the abdomen is usually divided, their number, and other circumstances connected with them. In the _Hippoboscidæ_, _Acaridæ_, _Phalangidæ_, and _Araneidæ_, the part we are considering is not divided into segments, though in some instances, as in _Gonyleptes_ and the cancriform _Epeiræ_[2131], they are represented by _folds_; but in the great majority of insects it consists of several dorsal and ventral pieces or segments, forming by their union the _annuli_ or rings into which it appears divided. The _number_ of these abdominal segments varies in different insects; I have noticed more than _twenty_ such variations, and probably there are many more. Before I give you them in detail, I must first observe that the dorsal and ventral segments, though sometimes they correspond in number, yet very often do not, the dorsal most commonly exceeding the ventral by a segment; in a few cases however the reverse takes place. In the sexes also there is frequently a difference in the number of segments, as has been before observed[2132]. I shall express the variations in question by two figures, the _first_ representing the number of _dorsal_ segments, and the _second_ the _ventral_--they usually only express the _apparent_ segments: perhaps a very general examination and dissection might bring many of them nearer to a common type.

1:1. _Chelonus._

3:3. _Chrysidæ_[2133].

4:2. _Leucospis_[2134].

5:5. _Syrphus_.

5:6. _Halictus_ ♀.

6:5. _Nepa._

6:6. { _Halictus_ ♂. { _Belostoma._

7:5. { _Curculio_ L. { _Cerambyx_ L.

7:6. _Dytiscus_ ♀.

7:7. _Ammophila_, &c.

8:6. { _Dytiscus_ ♂. { _Lucanus_, &c.

8:7. _Geotrupes_ Latr.

8:8. _Pimpla._

8:10. _Euchlora_ M^cL.[2135]?

8:13. _Scutigera._

9:5. _Carabus_ Latr.

9:6. _Gymnopleurus_ Ill.

9:7. _Perga_ Leach ♀.

9:8. _Perga_ ♂.

10:7. _Locusta_ Leach ♀.

10:8. --------------- ♂.

10:10. _Æshna._

11:7. _Phasma._

11:9. _Chelifer._

12:11. _Thelyphonus._

Many: _Myriapoda._

I shall next explain the articulation of the segments with each other, both that of the rings formed by the union of the dorsal and ventral pieces, and that of those pieces themselves. In general it may be stated with respect to the former, that each ring is suspended by ligament to that which precedes it; but this takes place in _three_ ways--in some the margins of the suspended rings _touch_ each other only, with little or no _inosculation_; in others the _dorsal_ segments only touch, and the base of each _ventral_ is covered more or less by the apex of the preceding one; and in others again the base of the whole ring, both above and below, is so covered, or inosculates. The first kind here mentioned you will find exemplified in _Melolontha_, _Geotrupes_, _Musca_, &c.; the second in _Scorpio_; and the third in _Staphylinus_, the _Hymenoptera_, and many others. In the _Coleoptera_, says M. Cuvier, speaking of the movements of the abdomen, the rings only touch each other at the margin, and the movement is very limited; whilst in the _Hymenoptera_ they are so many little hoops, which inosculate in each other as the tubes of a telescope, one third only of their extent often appearing uncovered[2136]. We see the reason of this structure when we consider the calls they have for greater powers of movement in this part in laying their eggs, and annoying their enemies and assailants; and also in the _Staphylinidæ_ to enable them to turn up their abdomen like a scorpion, both as a posture of attack, and to fold their wings: in all cases, however, as far as my observation goes, these animals, when they want to lengthen this part, can disengage the rings from almost all inosculation, so that no impediment remains to any movement.

The articulation of the dorsal and ventral segments with each other is next to be considered. In _Iulus_ and some _Centroti_ the ring appears to be formed of a single piece, with scarcely any trace of the existence of any such division; it is however almost universal, and is of _three_ descriptions; in the first the dorsal segments are united to the ventral _at_ the lateral margin or edge of the abdomen; in the second it is _above_ this margin, and in the third _below_ it. You will find that in _Fulgora_ and many other Homopterous _Hemiptera_ these segments unite at the margin, as they do likewise in _Cimex lectularius_ belonging to the other Hemipterous section; but in the rest of the Heteropterous tribes, the ventral segments turn upwards, and their union with the dorsal is in the back of the abdomen; in these the _Hemelytra_ and wings only cover the dorsal segments, leaving the edge, formed of the ends of the ventral, uncovered. The Lamellicorn beetles also, and many other _Coleoptera_, exhibit the same structure. To the last description, in which the dorsal segments turn down to meet the ventral, belong the _Lepidoptera_, _Locusta_ Leach; likewise _Sirex_, _Chrysis_, and many other _Hymenoptera_. The articulation between these segments is by means of an elastic membranous ligament, which usually is not externally visible; but in many instances, in which the connecting ligament is of a firmer substance, as in _Scorpio_, _Thelyphonus_, and _Phrynus_, it is very conspicuous, and in the latter genus exhibits many longitudinal folds, as it does likewise in _Gryllotalpa_, which must permit a vast extension of the abdomen. In this membrane, in some cases, as in _Dynastes_ M^cL., _Melolontha_, &c., the two or three first spiracles are fixed[2137]. In the _Hymenoptera_ and many other insects the dorsal segments do not unite by their _margin_ with the ventral, but the _end_ of each dorsal laps over that of the corresponding ventral.

_Dorsal segments_[2138]. I shall next notice the segments _seriatim_, in the order of their occurrence, beginning with the _dorsal_ ones. The most remarkable circumstance with respect to these that occurs to my recollection takes place in the Cancroid spiders (_Epeira cancriformis_, _aculeata_, &c.), in which the back of the abdomen is formed by a plate, in some extended in a transverse direction (_E. cancriformis_), in others in a longitudinal one (_E. aculeata_), of a much harder substance than the under side and quite flat, set with strong sharp spines, in the former species apparently moveable, and terminating behind in a piece resembling in some measure the scutellum of the _Stratyomidæ_ and similarly armed with a pair of spines[2139]: in _E. aculeata_ the sides of the abdomen, under the plate, have a number of longitudinal folds like those of _Phrynus_. In _Cryptocerus_, a genus of ants peculiar to South America, the _first_ segment, not reckoning the pedicle, forms almost the whole back of the abdomen, and the three last are so minute as scarcely to be distinguishable. Nothing very remarkable is exhibited by the other segments, except that in _Trichius_ the _penultimate_ is the largest; in some _Staphylinidæ_ (_S. splendens_) and _Brachini_ (_B. melanocephalus_) it is emarginate, and in the former tribe also often terminating in a white membrane. The _dorsal_ segment most worthy of notice is the last, which is called the _podex_; for though in general it is a minute piece, often retracted within the abdomen and invisible, as in many _Diptera_, yet sometimes it is the most conspicuous of the dorsal segments. It is most commonly triangular, and usually deflexed and forming an angle with a horizontal line; but in _Clytra_, _Chlamys_, and _Oryctes_, it is inflexed; in many Lamellicorns it is nearly vertical. In _Tettigonia_ F., many other Homopterous _Hemiptera_, and some _Hymenoptera_ (_Cimbex_), its sides turn down and become ventral; on its lower side it has in these a longitudinal cavity which receives the ovipositor in repose[2140]. In many other insects it unites with the last ventral segment, the _hypopygium_, to form a tube for that organ, as you will find in _Callidium violaceum_[2141], many _Muscidæ_, and _Thelyphonus_. As to its _termination_ the podex is sometimes bifid, _Blatta_; bipartite, _Ranatra_; mucronate, _Sirex_; acuminate, _Melolontha vulgaris_, _Trichius hemipterus_. Generally this part is flat; but the disk is elevated or gibbous in _Oryctes_ and some other Lamellicorns. In the majority of the _Coleoptera_ Order it is quite covered by the wings and elytra; but in many of the last-mentioned tribe, and sometimes the penultimate segment also, it is not covered by them[2142]. In some insects the piece we are considering appears to consist of _two_ segments; in the male of _Locusta morbillosa_ the whole podex is rhomboidal, but it is formed by two triangular pieces which articulate with each other; this structure permits the more easy elevation of the terminal one for the extrusion of the feces.

_Ventral Segments_[2143]. We are now to turn our attention to the _ventral_ segments of the abdomen. The first of them is what is called the _epigastrium_[2144] in the table. This part, according to M. Chabrier, is of considerable importance to the animal in flight, as, by its pressure against the trunk, not only regulating the movements of the abdomen, but as, in his opinion, contributing to push forward the trunk[2145] in the descent of the animal. It is remarkable only in the _Coleoptera_ and Heteropterous _Hemiptera_, to which my observations upon it will be confined. It may be stated as usually consisting of two articulations, that nearest the trunk being narrow, and in the Predaceous beetles[2146], as also in _Scutellera_, _Pentatoma_, &c., interrupted in the middle[2147]. In many _Lamellicorns_ this joint is concealed under the posterior _coxæ_, and with the anterior part of the second forms a hollow cavity for their reception; this last joint is what is properly the _Epigastrium_, the former, especially when distinct, being called in the table the _Hypochondria_. In _Sagra_ and _Brentus_ the _epigastrium_ is particularly conspicuous for its size, in the former occupying half, and in the latter nearly two-thirds of the under side of the abdomen; but in general it is distinguished from the remaining segments only by the central mucro or point that terminates it towards the trunk[2148], and which is received by a sinus of the _metasternum_; this point is generally minute and triangular, but in _Sagra_ it is large and rounded at the extremity, and in _Calandra_ it terminates nearly in a transverse line somewhat waving. It is most remarkable, however, in some species of the Heteropterous genus _Edessa_ F.; for in _E. nigripes_ and affinities it is a sharp _sterniform_ conical horn, which passing between the four posterior legs covers the end of the _promuscis_. In fact, this part appears a kind of abdominal _sternum_. In the _Cetoniadæ_, &c., the _Hypochondria_ unite before this mucro, and form a ridge which articulates with it, and dips towards the abdominal cavity; in _Scolytus_ the _epigastrium_ is much elevated from the rest of the ventral segments, so that the under side of the abdomen appears as if it were suddenly cut off, whence Herbst's awkward though not inexpressive name, _Ekkoptogaster_; this part in this genus has something of a posterior mucro.

The intermediate ventral segments exhibiting no very remarkable peculiarities, I shall pass them without further notice, and call your attention to the last, which is opposed to the _podex_, and which I have named the _hypopygium_[2149]. Though usually a _single_ small piece, in _Edessa_ and many _Pentatomæ_ it consists of _several_ plates; and in _Trichius_ it is very large: it is mostly _intire_, but in the male _Dytisci_ it is _cleft_; in _Lamia ocellata_ trilobed; in _Edessa_ tripartite; in _Centrotus Taurus_ it is boat-shaped and hollowed out to receive the stalk of the ovipositor. It is also generally in the same line with the body, but in _Xenos_ it is turned up and bent inwards[2150].

iv. _Shape._ With regard to _shape_, in some Orders the abdomen varies considerably; but the most general form is one that approaches to trigonal, so that a transverse section will be a triangle, with the vertex more or less obtuse, and the base more or less convex; some tendency to this form will often be found even in those insects whose abdomen appears almost as flat as a leaf, as in many _Aradi_. In the hive-bee the transverse section is almost an equilateral triangle; in _Belostoma grandis_ the disk of the under side of the part in question is longitudinally elevated into a trigonal ridge, the section of which is an equilateral triangle, the sides being quite flat. In general, in the vertical section of an abdomen, the vertex of the triangle points _downwards_, but in _Libellula_ F. it points _upwards_. In _Blatta_ this section is nearly lanceolate; in _Staphylinus olens_ it is a segment of a circle with the convex side downwards; in _Æshna_ F. with that side upwards; and in _Agrion_ the section is circular. In _Copris_, _Ateuchus_, &c., the abdomen is very short and thick; in _Staphylinus_ slender and long; in _Aradus_, _Nepa_, &c., depressed and flat; compressed in _Ophion_ and _Evania_; conical in _Cœlyoxis_; rhomboidal in many _Mantes_; boat-shaped in many _Lygæi_; fusiform in various _Papilionidæ_; lanceolate in some _Ichneumonidæ_, falcate in others; nearly round in _Diapria pupurascens_; ovate in _Lyrops_; elliptical in _Andrena_; oblong in many _Xylocopæ_; heart-shaped in the naked _Euglossæ_; triangular in _Dytiscus_; gibbous in _Flata_; and vaulted in _Chrysis_. At its base it is truncated in _Sirex_; retuse in most _bees_; forming the segment of a circle in _Andrena_; in general sessile, but in the majority of _Hymenoptera_, as has been already observed, terminating in a pedicle. The pedicle is very short in the _Andrenidæ_ and _Apidæ_; long in the _Sphecidæ_; thick in the _Formicidæ_; slender in _Evania_; fusiform in _Pelecinus_; clavate in _Ammophila_; campanulate in many _Vespidæ_; nodose in _Myrmica_[2151]; squamigerous in _Formica_[2152]: it sometimes also consists of _two_ joints, as in _Ammophila_ and many _Vespidæ_. As to _margin_, some have none, as _Centrotus_; in others, as _Dytiscus_, it is very narrow; in others again, wide and flat, as in the _Nepidæ_; in _Staphylinus_, &c., it is distinguishable only on the upper side of the abdomen; in _Locusta_ Leach only on the under side, though mostly intire; it is serrated in _Blatta_, sinuated in _Acanthia paradoxa_, and crenated in _Cerceris_.

v. _Proportions._ These vary greatly in the different tribes; in some the abdomen is long and slender, as in _Locusta_, and _Staphylinus_; disproportionably so in a remarkable degree in some _Agrionidæ_ from South America, as _A. lineare_, &c.[2153]; in others it is extremely short and thick, as in _Copris_, &c.; a mere appendage in _Evania_; it is shorter than the elytra in _Trox_; of the same length in most beetles; longer in _Melolontha_, _Hister_, &c.; disproportionably so in _Staphylinus_: though usually of the same width with the trunk, in many _Mantidæ_ it is much wider[2154]; and more slender in the _Libellulina_, _Myrmeleon_, &c.

vi. _Arms and Appendages_[2155]. These are various; and may be considered under the following heads: _processes_; _organs_ of _respiration_, _motion_ and _prehension_; _weapons_; and other _anal appendages_ the use of which is unknown.

1. _Processes._ Under this term I include all prominences of whatever kind, whether _tubercles_, _teeth_, _spines_, or _horns_, that arm any part of the abdomen. Many of these are _sexual_ characters, and have been sufficiently described in a former letter[2156]; I need not therefore detain you long on this head. Of the first kind is a remarkable elevation that distinguishes the second ventral segment of _Scolytus Destructor_ (_Ips Scolytus_ Marsh.) or of a species allied to it[2157]; in _S. pygmæus_ (_I. multistriatus_ Marsh.) the same segment is armed by a flat horizontal _tooth_ or horn; in an _Aradus_ from Brazil, before alluded to[2158] (_A. laminatus_ K. MS.), the margin of the abdomen is surrounded by eight flat subquadrangular laminæ; in another species figured by Stoll[2159], it is cut out into bays by a number of denticulated teeth; and in _Acanthia paradoxa_ by long spinose lobes[2160]. In _Edessa_ F., another genus of bugs, the abdomen usually terminates in four strong sharp dentiform spines, the intermediate ones being the shortest, and in some the _margin_ is also armed with spines[2161]; occasionally the anal spines are very long[2162]. In addition to the ventral horns before mentioned that distinguish the sexes of some insects[2163]; the males of the genus _Conops_, a two-winged fly, have, on the antepenultimate ventral segment, a singular process, varying in length and shape in the different species, standing nearly at right angles with the belly, convex towards the trunk, and concave towards the anus. De Geer supposes that with the anal extremity this forms a forceps with which this fly seizes the other sex[2164].

2. _Organs of respiration_[2165]. I shall defer my account of the _spiracles_, and other external respiratory organs, till I come to treat of the system of _respiration_ in insects, when every thing connected with that subject will be most properly discussed; but there are certain appearances in some insects, which at first sight seem to partake of the same character, but which being really independent of that vital function, may here have their place. If you examine the abdomen of the mole-cricket (_Gryllotalpa vulgaris_), you will easily discover the true spiracles in the folds of the _pulmonarium_, which separates the back of that part from the belly; if you next inspect the five intermediate segments of the latter, you will discover on each nearer the base a pair of oblique little channels, which precisely resemble closed spiracles. These may be denominated false or blind spiracles. Again, if you examine the pupa of any _Scutellera_ or _Pentatoma_, in which tribe the true spiracles are _ventral_, you will discover, placed in a square on the two or three intermediate _dorsal_ segments, four or six elevated points resembling spiracles, but not perforated, connected often by corrugations in the skin or crust[2166]; in the larvæ also of some _Reduvii_ the first minute dorsal segment, at each lateral extremity, has a similar elevation with a central umbilicus precisely resembling a spiracle, but still not perforated: another instance of false spiracles in this section of the _Hemiptera_, is furnished by _Aradus laminatus_ before mentioned, in the perfect insect; between the spiracle and the margin of each ventral segment is a white round callus, with a dark point resembling a perforation on its exterior side, and terminating internally in a channel covered by membrane leading to the disk of the segment, so that the whole in shape resembles a tobacco-pipe[2167]. A number of similar callosities with a central impression, but without any channel, variously disposed, are also to be found in another bug, _Rhinuchus compressipes_ K.[2168] In the Homopterous section of this Order, a series of impressed points, which may be easily mistaken for spiracles, are to be discovered on both sides of the abdomen, at the margin in _Centrotus_, in which the real spiracles are quite concealed.

In spiders, as we learn from Treviranus, the open _ventral_ spiracles of the scorpion are replaced by pseudo-spiracles; these in _Epeira Diadema_ are three pair of small black points: on the back of the abdomen also are _four_ pair, but in some species there are only _two_[2169]: the most remarkable, however, are exhibited by the cancriform spiders before noticed[2170]: in _Epeira cancriformis_, in the plate which covers the abdomen, they are dark red spots with an elevated rim and centre[2171] exactly resembling spiracles, except that they are not perforated; there are twenty-four of them, twenty arranged round the margin, and four in a square in the disk.

3. _Organs of motion._ In a former letter you were told that several insects are enabled to leap by means of _organs_ in their abdomen; I shall now describe such of them as require further elucidation. I then said that _Podura_ and _Sminthurus_, two apterous genera, take their leaps by means of an anal _fork_[2172]. In the former genus the fork consists of a single piece attached to the under side of the anus, and terminating in a pair of long slender sharp processes which articulate with it and form the fork or saltatorious instrument[2173]. In _Sminthurus_ the _tines_, as they may be called, of the fork do not articulate with the base, but are of the same piece and consist of two joints, the terminal one being flat and obtuse[2174]. _Machilis_ to the anal fork adds eight pair of ventral linear springs (_Elastes_), which are covered with hair or scales, and terminate in a bristle or two. I have on a former occasion mentioned the natatorious laminæ with which the anus of the larva of _Agrion_ and of some _Diptera_ is furnished[2175]; the same part in that of _Dytiscus_ ends in a pair of tapering organs, fringed on each side like the hind-legs of the imago[2176], which doubtless assist it in swimming; those respiratory foliaceous laminæ which so singularly distinguish the abdomen of the larvæ of _Ephemera_, like the legs of the Branchiopod _Crustacea_, are probably used in some degree as fins, and aid their motions in the water[2177]. Under this head may also be mentioned the many-jointed bristles that form the long tails[2178] of the fly that proceeds from these larvæ, whose interesting history I long since enlarged upon; for when they fly the two lateral ones diverge from the central one, and perhaps perform the same office as the tail feathers (_rectrices_) of birds. These bristles are also to be found in _Machilis_[2179], and probably, as its _leaps_ are almost as long as _flights_, for a similar purpose, to steady their motion. I may here lastly state that I once saw a _Cryptophagus_ (_Corticaria_ Marsh.), but I forgot to note the species, walking upon my window, which when it wanted to turn fixed itself to the glass by an inflated anal vesicle, and so accomplished its purpose.

4. _Organs of Prehension_[2180]. The abdominal organs of _prehension_ are various; but as the great body of them are connected with the sexual intercourse of insects, I shall not consider them till I come to treat on that subject. The only remarkable one that is common to both sexes is that of the earwig, which is too well known to every child to call for any long description. The external organs of _oviposition_ I shall also describe hereafter, and likewise those of _secretion_ that have not already been noticed.

5. _Weapons._ As the _stings_ of some _Hymenoptera_ are analogous to the _ovipositors_ of the majority of that Order, I shall consider them both together when I treat of the sexual organs of insects; but there is one, and that a tremendous one, not connected with those organs, which may be noticed here. I mean the sting of the _scorpion_. There appears to be some analogy between the poisonous fangs of one tribe of the Ophidian reptiles[2181], the mandibulæ of spiders[2182], the second pair of pedipalps, or the fangs of the _Scolopendridæ_[2183], and the organ in question[2184]; but the last possesses this peculiarity, that it is placed at the opposite extremity of the body, where it is preceded by a long jointed tail, which properly speaking is merely a continuation of the abdomen, since the spinal marrow, the intestinal canal, and the _pseudocardia_, are extended into it[2185]. Providence might have a double view in thus contracting the dimensions of this part of the abdomen; in the first place, the animal is by this enabled to turn its tail over its back preparatory to its inflicting a wound, and in the second, perhaps, this formation favours the sublimation of the venom, the long tail acting as an alembic for that purpose. This machine consists of six angular joints including the sting, the last but one being the longest, and the last inflated, as it were, at the base, and terminating in a sharp subulato-conical point which curves downwards, and has an orifice in a channel at the end on each side. Treviranus could not discover these orifices in the sting of _Scorpio europæus_[2186]; they may however be readily seen if viewed with a sufficiently high power, though not under a common pocket microscope. Whether the very slender, many-jointed, _real_ tail of the remarkable genus _Thelyphonus_ is used in any respect as a _weapon_, has not been ascertained: it is a filiform hairy organ consisting in some specimens of more than _twenty_ joints, the first being very much larger than the rest[2187].

6. _Appendages_[2188]. We are lastly to advert to those _appendages_ of the abdomen of which the use is not at present discovered. These are the styles (_styli_) of the _Staphylinidæ_; the leaflets (_foliola_) of the _Libellulina_; the floret (_flosculus_) of the _Fulgoræ_; the _cerci_ of the _Blattidæ_ and _Gryllina_; and the threads (_fila_) of _Machilis_: but having nothing important to add concerning them, the definitions of those terms will give you a sufficiently clear idea of them[2189]. As they are common to both sexes, if their use is connected with the sexual intercourse, it must be similar to that which Treviranus ascribes to the pectens of scorpions, they must be instruments of excitement.

* * * * *

And now, after this long discourse on the External Anatomy and structure of these little beings, you may think perhaps at first that the subject is exhausted; and that I must have discovered and described every part and every variation of every part of the crust of an insect. But when you go on to reflect what a comparatively small number of these creatures have fallen under my examination, and in those, after all my laborious and painful researches, from my limited faculties and other imperfections of our common nature, how much will probably have eluded my notice, you may conclude that thousands of facts still remain concealed to reward the patient assiduity of future investigators. Such are the immensity and variety of the works of the CREATOR in this department, that it would require a long life, and fill volumes upon volumes, to discover and give a description of all the peculiarities of structure of the insects that are already known; and could all that exist[2190] be so studied and explained in full detail, the library that the Calif Omar ordered to be burned at Alexandria could scarcely have contained more books than would be required to receive the results. But "who is sufficient for these things[2191]?" This is a question that the most able and most experienced physiologist must often feel disposed to put to himself when, lost in the intricate labyrinth of the works of his Maker, he sees all things arranged, "wheel within wheel," in an order that he can only _partially_ unravel, instead of tracing the "regular confusion" through all its windings. But glimpses of light, and points of irradiation, here and there discover to _fragments_ of the truth of things, and such vestiges of the grand system of the DEITY, as enable him in some degree to appreciate, and dispose him humbly to adore that WISDOM, POWER, and GOODNESS, that at first created and now sustains in its full beauty and harmony the WONDROUS WHOLE.

I am, &c.

END OF THE THIRD VOLUME.

Printed by Richard Taylor, Shoe-Lane, London.

FOOTNOTES:

[2125] _Anatom. Compar._ i. 450.

[2126] _Anatom. Compar._ i. 451.

[2127] De Geer notices something of the kind in _Cimbex femorata_. ii. 947.

[2128] It was omitted to be observed, when the supposed pneumatic pouches in the genus _Vespa_ were mentioned (see above, p. 585), that they have also a very conspicuous metaphragm, as probably have most _Hymenoptera_, to which the muscles that move the wings are attached.

[2129] PLATE IX. FIG. 13. _F´_ is the tendon, G´ the aperture in the abdomen C, and a, the aperture in the trunk B.

[2130] PLATE XV. FIG. 11. _Linn. Trans._ xii. _t._ xxii. _f._ 16.

[2131] Surely these _Epeiræ_, of so different a habit from the rest, form a distinct genus?

[2132] See above, p. 339.

[2133] There is reason to suppose that in _Chelonus_ and the _Chrysidæ_ several segments are retracted within the abdomen, and if the cavity of its under side in the latter be examined, it will be discovered that the _epigastrium_ is divided in the middle into two pieces, and that both the sides of this and the following segments are covered by three narrow accessory plates, one to each, the last being the shortest. De Geer (ii. 833.) describes _Chrysis ignita_ as having _four_ abdominal rings; but this is only in _appearance_, there being really only _three_. This appearance is produced by the apex of the last dorsal segment being more depressed and marked with several deep little excavations that look like holes. In some species of _Stilbum_ this segment consists as it were of three ridges or steps.

[2134] In this genus the ventral segments are replaced by a long narrow central plate, succeeded by a minute one.

[2135] In this genus the bed of the posterior coxæ appears to consist of two segments, which are beautifully fringed with parallel short bristles.

[2136] _Anatom. Compar._ i. 451.

[2137] PLATE VIII. FIG. 9. _A´´_, _B´_.

[2138] Ibid. FIG. 5. _A´´._

[2139] PLATE XV. FIG. 10.

[2140] Reaum. v. _t._ xvii. _f._ 14. _a. a._

[2141] _Linn. Trans._ v. _t._ xii. _f._ 15.

[2142] Daldorf (_Asiatic Society's Trans._ vii.) has divided _Geotrupes_ into two families, one with the podex _covered_ (_G. vernalis_, &c.) which he calls _modesti_, the other with it _uncovered_ (_G. stercorarius_, &c.) which he calls _obscæni_.

[2143] PLATE VIII. _E´._

[2144] Ibid. _D´._

[2145] _Sur le Vol des Ins._ c. i. Addend. 299.

[2146] In _Dytiscus marginalis_ the upper side of the margin of the _Hypochondria_ is curiously cut into transverse corrugations.

[2147] PLATE VIII. FIG. 6. _C´._

[2148] Ibid. _B´´._

[2149] PLATE VIII. _L´._

[2150] _Linn. Trans._ xi. _t._ ix. _f._ 15. _b._

[2151] PLATE IX. FIG. 18. _I´._

[2152] Ibid. FIG. 17. _H´._

[2153] Rœmer. _Genera_, &c. _t._ xxiv. _f._ 4.

[2154] Stoll _Spectr._ _t._ vii.

[2155] PLATE XV. FIG. 10-23.

[2156] See above, p. 339--.

[2157] This tubercle I find only in a specimen from Sweden, sent to me by Major Gyllenhal, but not in any British one I possess. In this specimen the declivity before mentioned (see above, p. 709.) is observable in the _first_ segment, but in the others it is formed by the _second_.

[2158] See above, p. 617.

[2159] _Punaises_, _t._ xiii. _f._ 84.

[2160] Stoll _Punaises_, _t._ xiii. _f._ 101.

[2161] _Ibid._ _t._ xvii. _f._ 117.

[2162] _Ibid._ _t._ xxxvi. _f._ 253.

[2163] See above, p. 339--.

[2164] De Geer, vi. 260. _t._ xv. _f._ 8. _d._

[2165] PLATE XXIX.

[2166] PLATE XXIX. FIG. 22. is part of the back of the abdomen of the pupa of a _Pentatoma_. _a_ the pseudo-spiracle, _b_ the connecting corrugations.

[2167] Ibid. FIG. 24. _a._

[2168] Ibid. FIG. 27. _a._

[2169] Treviranus. _Arachnid._ 23--.

[2170] See above, p. 702, 706.

[2171] PLATE XXIX. FIG. 26. represents one of them.

[2172] VOL. II. p. 319--.

[2173] PLATE XV. FIG. 14. _M´´._ De Geer, vii. _t._ ii. _f._ 5, 10, 21.

[2174] Ibid. _t._ iii. _f._ 4, 14.

[2175] See above, p. 154.

[2176] PLATE XVIII. FIG. 5. _a._

[2177] PLATE XXIX. FIG. 3, 4. De Geer, ii. _t._ xvii. _f._ 12. and _t._ xviii. _f._ 2.

[2178] Ibid. _t._ xvi. _f._ 8-13.

[2179] PLATE XV. FIG. 16. _S´´._

[2180] Ibid. FIG. 12. _L´´._

[2181] _Philos. Trans._ 1818. _t._ xxii.

[2182] _N. Dict. d'Hist. Nat._ ii. 275--. Hoole's _Leeuwenh._ i. _t._ ii. _f._ 19. I.

[2183] Leeuwenh. _Epist._ 17. Octobr. 1687. _f._ 10. C.

[2184] Hoole's _Leeuwenh_. i. _t._ v. _f._ 12, 13.

[2185] Treviranus, _Arach._ 4.

[2186] Treviranus, _ubi supr._ 14.

[2187] In my specimen including the first joint there are _twenty_, and some seem to have been broken off. In Rœmer's figure (_Genera_, _t._ xxix. _f._ 11.) there are only _ten_. Perhaps they vary in number according to the age of the animal.

[2188] PLATE XV. FIG. 13, 16, 17.

[2189] See above, p. 391--.

[2190] I have heard it stated upon good authority that 40,000 species of insects are already known, as preserved in collections. How great, then, must be the number existing in this whole globe!

[2191] 2 Cor. ii. 16.

EXPLANATION OF THE PLATES[2192].

PLATE VI.[2193]

FIG.

1. Head of _Mylabris_. Upper side, or _face_.

2. ------------------- Under side, or _subface_.

3. Trophi of _Dytiscus_. _Six_ pieces.

4. Head of _Locusta_. Face.

5. ------------------ Front view, to exhibit the mouth.

6. Trophi of ditto. _Seven_ pieces.

7. Head of _Cicada_. Face.

8. ------- _Scutellera_. Subface.

9. Trophi, or _promuscis_ of _Hemiptera_. _Three_ pieces.

10. Head of _Æshna_. Face.

11. ---------------- Front view.

12. Trophi of ditto. _Seven_ pieces.

13. ------ or _antlia_ of _Lepidoptera_. _Four_ pieces.

14. ------ of _Panorpa_. _Three_ pieces.

PLATE VII.[2194]

FIG.

1. Head and trophi of _Phryganea_ L. Face.

2. ------------------ _Vespa Crabro_. Ditto.

3. Trophi of _Bombus_.

4. Head of _Tabanus_ L. Face.

5. Trophi or _proboscis_ of ditto. (Reaum.)

6. ------------------------ _Bombylius_[2195].

7. Head of _Oxypterum_. Face.

8. Head of _Pulex_, with its antennæ and trophi, or _rostrulum_. Side view.

9. ------- _Araneidæ_, with the trunk.

10. Trophi of ditto.

11. Head of _Scolopendra morsitans_. Subface.

12. ---------------- --------------- Front view, to show the mouth.

13. Trophi of ditto.

14. Pharynx of _Pentatoma_. (Savigny.)

PLATE VIII.[2196]

FIG.

1. Prothorax of _Lucanus_. a. Apex. b. Base. c d. Sides. _a._ Disk.

2. Antepectus of ditto.

3. Alitrunk of ditto. Upper side. a. A piece between the metathorax and metaphragm.

4. ------------------ Under side.

5. Abdomen. Upper side, or _tergum_.

6. -------- Under side, or _venter_.

7. Antepectus of _Hydrophilus piceus_.

8. Alitrunk of ditto. Under side, to show the metasternum.

9. Abdomen of _Dynastes Aloeus_, to show the dorsal and ventral spiracles.

10. Prothorax of _Locusta_. a. Apex. b. Base, c c. Sides.

11. Antepectus of ditto, to show the prosternum.

12. Alitrunk of ditto. Upper side.

13. ------------------ Under side.

14. ------------------ Lateral view. VOL. III. p. 48.

15. Abdomen of ditto. Lateral view.

16. Alitrunk of _Cicada_ Latr. Upper side.

17. -------------------------- Under side. a. The piece in the ♀ corresponding to the drum-covers of the ♂.

18. Abdomen, and part of postpectus of ♂ ditto. Under side, to show the drums. VOL. II. p. 405--.

19. Abdomen, and part of postpectus of ♂. Lateral view, with the covers removed to show the machinery.

20. Alitrunk. Upper side. _Pentatoma_.

PLATE IX.[2197]

FIG.

1. Alitrunk of _Cossus ligniperda_. Upper side.

2. Part of ditto, to show the mesophragm.

3. ------------- Under side.

4. Patagia of _Lepidoptera_. Upper and under sides. VOL. III. p. 368, 539.

5. Tegulæ of ditto. _Two_ species. VOL. III. p. 378.

6. Prothorax of _Æshna_. a. The base elevated and forming an obtuse angle with the rest.

7. Alitrunk of ditto. Upper side. a. Two elevated areas of the posterior parts of the collar, strengthened by a marginal ridge and denticles, internally connected by an elastic ligament, apparently to aid and sustain the powerful action of the wing-muscles.

8. ------------------ Lateral view. a. A piece by which the mid-leg is connected with the scapular. VOL. III. p. 48, 565.

9. Part of the abdomen of _Libellula_.

10. Trunk of _Semblis_ F. Upper side.

11. Alitrunk of _Vespa Crabro_. Upper side. a. Aperture in the trunk for the passage of the ligament that elevates the abdomen.

12. Lateral view of ditto.

13. --------------- posterior part of ditto, and of the base of the abdomen, to show the above apparatus. a. The aperture. VOL. III. p. 701.

14. Head and part of the manitrunk of _Tenthredo_ L. to show the membrane _a._ representing the prothorax. VOL. III. p. 550--.

15. Alitrunk of _Xiphydria_. Upper side.

16. ------------------------ Lateral view.

17. Part of trunk and abdomen of _Formica_, to show the _squama_. VOL. III. p. 389. 3.

18. ------------------------- of _Myrmica_, to show the _nodus_. VOL. III. p. 389. 4.

19. Alitrunk of _Musca_. Upper side. a. _Alula_ or winglet.

20. Metathorax of ditto.

21. Alitrunk of ditto. Lateral view.

22. Abdomen of ditto. Venter.

PLATE. X.[2198]

N.B. In this plate the _red_ points out the _costal_, and the _yellow_ the _anal_ areas, the _intermediate_ being _uncoloured_.

FIG.

1. Elytra, a. Base. b. Shoulder. c. Lateral margin. d. Apex.

2. Tegmina. _Blatta_.

3. Hemelytra. _Pentatoma_.

4. Wing. _Coleoptera._ a. An insulated nervure. VOL. III. p. 625.

5. ----- _Dermaptera._

6. ----- _Lepidoptera._

7. ----- _Neuroptera._

8. ----- _Hymenoptera. Tenthredo_ L.

9. ------------------- _Bombus._

10. Under wing. _Hymenoptera._

11. --------------------------- _Proctotrupes._

12. ----------- _Diptera. Tipula._

13. --------------------- _Psychoda._ VOL. III. p. 645.

14. --------------------- _Musca._ a b. Two areolets between the costal and mediastinal nervures. c. Areolet between the mediastinal and postcostal nervures. d. Areolet between the postcostal and subcostal nervures, e. Open areolet. VOL. III. p. 634.

15. Under wing. _Diptera._ _Stratyomis._ a b. The two areolets between the costal and postcostal nervures; the mediastinal being nearly obsolete. c. Middle areolets crowned by a small one, d.

PLATE XI.[2199] _Antennæ._

FIG.

1. Setaceous. 2. Capillary. 3. Filiform. 4. Incrassate. 5. Fusiform. 6. Prismatic. 7. Ensiform. 8. Falciform. 9. Moniliform. 10. Dentate. 11. Serrate. 12. Imbricate. 13. Distichous. 14. Pectinate. 15. Duplicato-pectinate. 16. Ciliate. 17. Flabellate. 18. Ramose. 19. Furcate. 20. Auriculate. _a._ The _auricle_. 21. Palmate. 22. Irregular. 23. Perfoliate.

PLATE XII. _Antennæ._

FIG.

1. Capillaceous. 2. Mucronate. 3. Uncinate. 4. Clavate. 5. Nodose, or Biclavate. 6. Convolute. 7. Geniculate. 8. Capitate with a tunicate knob. 9. Capitate with a solid knob. 10. Capitate with a perfoliate knob. 11. Filiform. 12. Globiferous. 13. Connate. 14. } 15. } Setigerous. 16. Subulate. 17. } 18. } Filate, simple. 19. Filate, compound. _a._ Joints. 20. Filate. 21. Aristate. Setarious _a._ Bristle. 22. Aristate. Plumate _a._ Bristle. 23. Stupeous. VOL. III. p. 646. 24. Plumose. 25. Scopiferous. _a._ Brush. 26. Barbate. 27. Verticillate. 28. Inflated. 29. Auriculate. _a._ Auricle.

PLATE XIII.[2200]

1. Unguiculate feeler. _Gonyleptes._ _a._ Claw.

2. Securiform ditto. _Cychrus._ _a._ Terminal joint.

3. Inflated ditto. _Araneidæ_ ♂. _a._ ditto.

4. Lunulate ditto. _Oxyporus._ _a._ ditto.

5. Dentate mandible. _Megachile._

6. Suctorious ditto. Larva of _Dytiscus_. _a._ Aperture.

7. Prosthecate ditto. _Staphylinus._ VOL. III. pp. 356, 439.

8. Trophi of _Curculio_ L.

9. Pedunculate eyes. _Diopsis._ _a._ Footstalk.

10. Compound ditto. _Muscidæ._ VOL. III. p. 494. 3.

11. Conglomerate ditto. _Iulus._ Ibid. p. 494. 2.

12. Rostrate head. _Balaninus._

13. Capistrate ditto. _Nitidula._

14. Clypeate ditto. _Copris._

15. Lychnidiate ditto. _Fulgora._

16. Buccate ditto. _Myops._ _a._ The inflated part.

17. Cruciate prothorax. _Locusta._

18. Cucullate and alate ditto. _Tingis._

19. Subulate elytra. _Sitaris._

20. Ampliate ditto. _Lycus._ #/

PLATE XIV.[2201]

FIG.

1. Ideal wing, to exemplify painting. VOL. IV. p. 286--. a. Anterior or exterior margin. b. Interior ditto. c. Posterior ditto. d. Humeral angle. e. Scutellar ditto. f. Posterior ditto. g. Anal ditto. _a._ Articulate _fascia_, or band. _b._ Macular ditto. _c d._ Sesquialterous ditto. _d e._ Sesquitertious ditto. _f._ Dimidiate ditto. _g._ Abbreviate ditto. _h._ Pyramidate ditto. _i._ Supercilium. _k._ Hastate pupil. _l._ Compound eyelet or _ocellus_. _m._ Nictitant ditto. _n._ Simple ditto. _o._ Annulet. _p._ Bipupillate eyelet. _q._ Sesquialterous ditto. _r._ Double ditto. _s._ Caudate wing. _t._ Pupil. _u._ Iris. _v._ Atmosphere.

2. Reversed wings. _Gastrophaca._

3. Digitate ditto. _Pterodactylus._

4. Falcate ditto. _Attacus._

5. Saltatorious leg, with loricate thigh. _Locusta._

6. Natatorious ditto. _Dytiscus._

7. Ambulatorious ditto. _Lucanus._

8. Prehensorious ditto. _Gonyleptes._

PLATE XV.[2202]

FIG.

1. Laminate coxa. _Haliplus._

2. Alate tibia. _Lygæus phyllopus_, a. The appendage.

3. Clypeate ditto. _Crabro_ ♂. a. The clypeus. VOL. III. p. 334.

4. Dolabriform ditto. _Curculio maritimus_ E.B.

5. Fossorious leg, with palmate tibia. _Clivina._ VOL. II. p. 365.

6. --------------- with digitate ditto. _Gryllotalpa._ Ibid. p. 366.

7. Chelate feeler. _Scorpio._

8. Scutate tarsus. _Hydrophilus piceus_ ♂. VOL. III. p. 336.

9. Patellate ditto. _Dytiscus marginalis_ ♂. a. Cups. Ibid. p. 336, 694--.

10. Obumbrate _abdomen_. _Epeira cancriformis._

11. Retracted ditto. _Gonyleptes._

12. Cheliferous tail. _Panorpa_ ♂.

13. Flosculiferous ditto. _Fulgora._

14. Saltatorious ditto. _Podura._

15. Folioliferous ditto. _Æshna._

16. Cauduliferous, and filiferous ditto. _Machilis._

17. Styliferous ditto. _Staphylinus._

18. Unciferous ovipositor. _Locusta._

19. Ensate ditto. _Acrida._

20. Navicular ditto. _Cicada._

21. Serrulate ditto. _Tenthredo_ L.

22. Telescopiform ditto. _Chrysis._

23. Anal apparatus of _Blatta_.

PLATE XVI.[2203]

FIG.

1. Extricated ovipositor. _Pimpla._ _Two_ pieces.

2. Telescopiform ditto. _Stomoxys calcitrans?_ (Reaum.)

3. -------------------- _Œstrus._ (Ibid.) VOL. I. p. 150.

4. Semicomplete pupa. _Cicada._

5. Subsemicomplete ditto. _Libellula._ _a._ Mask. VOL. III. p. 125--.

6. Incomplete ditto. _Hydrophilus._ (Lyonnet.)

7. ----------------- _Myrmeleon_ emerging from its cocoon. (Reaum.)

8. ----------------- _Vespa vulgaris._

9. ----------------- _Chironomus plumosus._ (Reaum.) _a b._ Respiratory plumes.

10. Obtected pupa. _Apatura Iris._

11. -------------- _Vanessa Urticæ._ _a._ Head-case with _two_ points.

12. -------------- _Gonepteryx Rhamni._ _a._ Head-case with _one_ point.

13. Obtected pupa. _Sphinx Ligustri._ _a._ The tongue-case. _b._ The eye-case. _c._ The trunk-case. _d._ First segment of the abdomen. _e._ The adminicula. _f._ The mucro, or point of the tail. VOL. III. p. 249--.

14. Hairy obtected pupa of _Laria fascelina_.

PLATE XVII.[2204]

FIG.

1. Coarctate pupa. _Œstrus hæmorrhoidalis._ (Reaum.)

2. --------------- _Stratyomis chamæleon._ (Ibid.) _a._ The pupa as formed within the skin of the larva.

4. Oviform body which many pupæ of _Diptera_ at first assume under the skin of the larva. (Ibid.). VOL. III. p. 235.

3. The same when the parts begin to show themselves. (Ibid.)

5. Cocoon of _Saturnia pavonia_. _a._ Pupa. _b._ Threads that close the orifice. VOL. III. p. 217, 279.

6. Loose and irregular ditto, of _Arctia villica_. Ibid. p. 220.

7. Boatshaped ditto, of _Tortrix prasinana_. Ibid. p. 221.

8. Network ditto, attached to the stalk of a plant.

9. Ditto, imitating the scales of fish. (Reaum.) VOL. I. p. 462.

10. Spiral case of _Trichopterous_ larva, formed of pieces of leaf. (De Geer.)

11. Grate spun by these larvæ to prevent ingress. (Ibid.) VOL. II. p. 264.

12. Chilopodimorphous larva of _Melolontha vulgaris_. VOL. III. p. 163.

13. Araneidiform? ditto of _Cicindela campestris_. Ibid. 152, 163.

PLATE XVIII.[2205]

FIG.

1. Anoplurimorphous larva. _Chrysomela Populi._ _a._ _Osmateria_, or scent organs. VOL. II. p. 245. III. p. 163, 166.

2. Anoplurimorphous larva. _Cassida_. _a_. The fecifork covered with excrement. VOL. IV. p. 353. 5.

3. Helminthimorphous or vermiform ditto of _Balaninus Nucum_. VOL. III. p. 163.

4. Chilognathimorphous ditto of _Elater Segetum_. _a. a._ Spiracles.

5. Decapodimorphous ditto of _Dytiscus marginalis_. VOL. III. p. 165.

6. Chilopodimorphous ditto of _Staphylinus_? _a._ Anal proleg.

7. Amphipodimorphous ditto of _Acrida_. VOL. III. p. 165.

8. Larva of _Zelus_.

9. Helminthimorphous ditto. _Apis mellifica_. (Reaum.)

10. Larva of _Sirex_.

11. -------- _Tenthredo_ L. (Reaum.) _a._ 6 legs. _b._ 16 prolegs.

12. -------- _Sphinx._ _a._ 6 legs. _b._ 10 prolegs. _c._ Anal horn.

13. Spinose ditto of _Vanessa Io_.

PLATE XIX.[2206]

FIG.

1. Larva of _Papilio Machaon_, _a._ Its retractile osmaterium emerging from its neck. VOL. II. p. 244--. III. p. 148.

2. Larva of _Cerura Vinula_. _a._ Its anal mastigia. VOL. III. p. 151.

3. Onisciform ditto of _Thecla Rubi_.

4. Larva of _Stauropus Fagi_. (Rösel.) VOL. III. p. 133. note^d.

5. -------- _Notodonta ziczac._ (Reaum.)

6. -------- _Laria fascelina._ _a._ Pencil of hairs, _b._ Verricules of ditto. _c._ Fascicule of ditto. VOL. IV. p. 277. 3, 5, 7.

7. -------- of one of the Geometers in their attitude of surveying.

8. Araneidiform larva of _Myrmeleon_. (Reaum.)

9. Larva of _Culex pipiens_. (Reaum.) _a._ Tail. _b._ Respiratory apparatus.

10. ----- of _Chironomus plumosus_. (Reaum.) _a._ Respiratory organs.

11. ----- of a _Volucella_ inhabiting the nests of humble-bees. (Reaum.) _a._ Anal radii.

12. ----- of _Elophilus pendulus_. (Reaum.) _a._ Respiratory tubes.

13. ----- of _Stratyomis Chamæleon_. (Swamm.) _a._ Plumes of respiratory orifice.

PLATE XX.[2207]

FIG.

1. Larva of a _Musca_.

2. -------- an _Œstrus_.

3. Egg of _Vanessa Urticæ_. (Sepp.)

4. ------ _Hipparchia Pilosellæ_. (Ibid.)

5. ------------------ _Hyperanthus_. (Ibid.)

6. ------ _Geometra Cratægata_. (Ibid.)

7. ------ _Pieris Brassicæ_. (Ibid.)

8. ------ _Hipparchia Ægeria_. (Ibid.)

9. ------ _Ourapteryx Sambucaria_. (Ibid.)

10. ------ _Noctua nupta_. (Ibid.)

11. -------------- _Fraxini_. (Ibid.)

12. ------ _Geometra prunaria_. (Ibid.)

13. ---------------- _armillata_. (Ibid.)

14. ------ _Lasiocampa neustria_. (Reaum.)

15. ------ _Hipparchia Jurtina_. (Sepp.)

16. ------ _Pentatoma_. _a._ Bow-shaped spring, by which the operculum is thrown off. VOL. III. p. 104.

17. ------ _Apis mellifica_. (Reaum.)

18. ------ _Culex pipiens_. (Ibid.) _a._ Summit.

19. ------ _Scatophaga_. (Ibid.) _a a._ Auricles.

20. Necklace of eggs. VOL. III. p. 67.

21. Egg of _Tipula oleracea_. (Reaum.)

22. ------ _Ophion luteum_. (De Geer.) VOL. IV. p. 213--.

23. ------ _Nepa cinerea_. (Swamm.)

24. Jelly, with a necklace of eggs running in a spiral direction from end to end, taken out of the water.

25. Jelly of more consistence, enveloping the eggs of _Phryganea atrata_. VOL. III. p. 68.

Printed by Richard Taylor, Shoe-Lane, London.

FOOTNOTES:

[2192] Recourse must be had to the synoptical table of the nomenclature of the parts of the external crust of Insects (VOL. III. p. 354) for the explanation of the reference letters not here given.

[2193] VOL. I. p. 394--. III. p. 355--, 394--. IV. p. 305--.

[2194] Ibid.

[2195] Probably e´ is resolvable into two pieces.

[2196] VOL. III. p. 367--, 529--. IV. p. 326--.

[2197] VOL. III. p. 367--, 529--. IV. p. 326--.

[2198] VOL. II. p. 347--. III. p. 372--, 595--.

[2199] VOL. III. p. 366, 510--. IV. p. 316--.

[2200] VOL. IV. p. 307. iii, iv. 309. b. 310. d. 313. viii. 328, 334.

[2201] VOL. IV. p. 286--, 338, 345--.

[2202] Ibid. p. 345--, 350--.

[2203] VOL. IV. p. 351. ii. III. LETTER XXXII. VOL. I. p. 65--.

[2204] _Ubi supr._

[2205] VOL. III. LETTER XXXI.

[2206] VOL. III. LETTER XXXI.

[2207] _Ubi supr._ and LETTER XXX.

Tanscriber's Notes:

Obvious punctuation and spelling errors have been fixed throughout.

Inconsistent hyphenation is as in the original.

The Errata mentioned on Page vi for this volume and Page viii for Volumes I and II have been made to the appropriate volumes.

Elements in the Figures that have an asterisk above them are referred in the text as a superscipt asterisk, since most fonts won't display the asterisk above.

Footnote 953: There is no anchor for this in the original, left as is.

Footnote 1553: There is no anchor for this in the original, left as is.