1.AraneideaMcL. (AraneaL.,AraneidæLatr.) TheAraneidea, or spiders, seem resolvable intotwosuborders,—theSedentariesand theWanderers; thus forming, perhaps, what Mr. MacLeay would denominate the normal groups of a circle ofArachnida.
Def.Mandiblesarmed with a perforated claw.
HeadandTrunkcoalite.
Palpipediform, anterior pair without claws.
Abdomenwithout segments or elongated tail.
Spiraclestwo[1251].
Anusfurnished with an apparatus for spinning[1252].
2.ScorpionideaMcL. (ScorpioL. Latr.)
Def.Mandibleschelate.
HeadandTrunkcoalite.
Anterior Palpichelate[1253].
Posterior Palpipediform.
Pectenstwo[1254].
Abdomendivided into segments and terminating in a jointed tail, armed at the end with a sting[1255].
Spiraclesfour pairs.
3.Galeodea.
Def.Headdistinct[1256].
Eyestwo.
Mandibleschelate with dentated chelæ.
Palpipediform, the anterior pair thickest with a retractile sucker.
Trunkconsisting of two principal segments, with a minute supplementary posterior one[1257].
Spiraclestwo placed in the trunk[1258].
Pseudo-pectenstwo[1259].
Abdomendivided into segments.
Anusunarmed and without a spinning apparatus[1260].
4.Phrynidea.
Def.Mandiblesunguiculate.
Anterior Palpichelate or unguiculate[1261], very robust.
Posterior Palpipediform, very long and slender.
Abdomendivided into segments.
Spiraclestwo pairs.
Anusterminating in a mucro, and sometimes in a filiform jointed tail without a sting at the end.
v. Having considered theOrdersinto whichInsectaandArachnidamay be divided, I am next to give you some account of thegroupsinto which each is further resolvable. To draw out, however, a complete scheme of these would be deviating from my province, and extendthis letter to an enormous length. Indeed, to give thenaturalprimary and subordinate sections of every Order, would require a knowledge of the subject to which no Entomologist has yet attained. I shall therefore only say something general upon them, and refer you to an example of each kind of group.
Previously to the groups themselves theirnomenclatureclaims our attention. M. Latreille in his last arrangement ofAnnuloseanimals has divided his Orders intoSections;Families;Tribes; andGenera: his tribes he has often further subdivided into lesser sections, represented by capital and small letters, &c.[1262]. Mr. MacLeay, discarding the term section, hasTribes;Races(Stirps);Families;Genera, andSubgenera[1263]. But as in descending from theOrderto the lowest term, or thespecies, a series of groups gradually diminishing in value, which require a greater number of denominations than have yet been employed by Entomologists, often occur, I think we may with benefit to the science add to the list. I would therefore propose the following primary and subordinate divisions of an Order: 1.Suborder; 2.Section; 3.Subsection; 4.Tribe; 5.Subtribe; 6.Stirps; 7.Family; 8.Genus; 9.Subgenus. I would further propose that each of these successive groups should have a name always terminating alike, so that the value of the group when spoken of might always be known by the termination:—thus if a subclass end inata, a suborder might end inita; a section inana, a subsection inena; a tribe inina, a subtribe inona; a stirps inuna; and a family inidæ; the genera being left free.
With regard to theircharacters, we are not to place our groups upon Procrustes' bed, and lop or torture them to accommodate them to every standard we may have fixed for them: assuming one set of characters for suborders, another for tribes, and so for every other group; for the value of characters varies,—those that in some cases are common to anOrder, in others indicate onlysections, ortribes, orgeneraandspecies, or sometimes evensexes. What is constant in one group is not so in another, andvice versâ; so that it is a vain labour to search for auniversalcharacter. If it is our wish really to trace the labyrinth of nature, we can only accomplish it by a careful perusal and examination of her various groups. It is singular how much and how far various Entomologists, and those of the very highest class, have been misled by a kind offavouritismto give too universal a currency to certain characters for which they have conceived a predilection. Some have been the champions of theantennæ; others of thetrophi; others again of thewings; and others of themetamorphosis. These are all characters which within certain limits lead us right, and are an index to a natural group; but if we follow them further, we leave the system of nature, and are perplexed in the mazes of amethod[1264].
Let us now see whether we can pitch upon any suborder which will afford an example of every group that we have lately named. Mr. MacLeay, from a consideration of the larvæ of that Order, has divided theColeopterainto five primary groups that may be denominatedSuborders. Whether these are all natural groupshas not yet been made sufficiently evident. It answers my present purpose, however, to assume it as proved. I select therefore hisChilopodimorphafor my suborder, altering the name as above proposed toChilopodimorphita: for mySectionI take the Predaceous beetles, orAdephagaof M. Clairville, distinguished by having the upper lobe of their maxillæ biarticulate and palpiform;—these I would denominateAdephagana, or devourers. They consist of two groups forming two subsections, the oneterrestrialand the otheraquatic; which I would name, following Mr. MacLeay,GeodephagenaandHydrodephagena. These two subsections are each resolvable into twoTribesconstituted by Linné's four generaCicindelaandCarabus;DytiscusandGyrinus. The first tribe, remarkable for the swiftness of theirflight, I would nameEupterina, or fliers; the second, equally noted forrunning,Eutrechina, or runners; the thirdEunechina, or swimmers; and the fourthGyronechina, or swimmers in a circle. The second of these groups, theEutrechina, are resolvable into two other groups orSubtribes; one distinguished by having the cubit or anterior tibianotched, (which, from their being in general not very brilliant in colour, I would callAmaurona, or obscure); the other having the cubit without a notch, (which, from the brilliancy of many of them, I would nameLamprona, or splendid). These subtribes are both further resolvable into two or moreraces(Stirpes). I select that to which thecrepitantEutrechinabelong, containing those which from their usually truncated elytra MM. Latreille and Dejean have namedTruncatipennes[1265]: these, to shorten the name, I callTruncipennuna.This brings us down to the lowest group formed out of genera and subgenera: or thefamily, which from its principal genus is namedBrachinidæ, and which leads us to thegenus Brachinus, and thesubgenus Aptini. Thus we get the following scale, expressing every division of an Order, till we arrive at its lowest term, or thespeciesthat compose it.
SuborderChilopodimorphitaMcL.SectionAdephaganaClairv.SubsectionGeodephagenaMcL.TribeEutrechinaSubtribeAmauronaStirpsTruncipennunaLatr.FamilyBrachinidæGenusBrachinusSubgenusAptini.
In the construction of this scale I have endeavoured to steer clear of being led by any system, but, with the exception of theSuborder, which I assume, to resolve it into natural groups gradually decreasing in value, or tending to the lowest term, which appear all of them tohave been considered as such by preceding Entomologists. The fourTribesinto which the two subsectionsGeodephagenaandHydradephagenaappear resolvable, are not only distinguished by the characters of the perfect insect, but likewise by those of their larvæ, which are constructed on four distinct types; those of theGyronechinabeing the most perfectly Chilopodimorphous of the whole, and those of theEunechinathe least so[1266]. The former appear rather to form an osculant tribe, or one without the circle, than one within it; and to be going off towards another section, includingHydrophilus,Sphæridium, &c. I must observe, that betweenDytiscusandHydrophilusthere is a striking agreement both in their form and habits in the larvæ[1266], and even in several characters in the perfect insect; so as in many respects to generate a doubt whether they ought not to enter the same circle and to follow each other. Yet the change of habits in the latter, which from a carnivorous larva becomes a herbivorous beetle; the consequent change of structure in their oral organs, their antennæ, and other striking differences; and the evident intervention of theGyronechinaand some other osculant tribes between the two, forbid their union in one and the same circle.
vi. I need not say more on those larger groups of an Order which conduct us to what are denominated itsgenera; but upon these last it will not be a waste of your time to enlarge a little. In the last edition of theSystema Naturæ, and in its appendixes, Linné has described 2840 species ofInsectaandArachnida, which he divided into 83 genera, allowing upon an average nearly 35 species to each genus. From the paucity of the materials, therefore, of which his system was constructed, there was no loud call upon him for numerous genera. But now more than thirty times that number are said to have found a place in the cabinets of collectors[1267], and there is good reason for thinking that perhaps half that are in existence are as yet undiscovered;—this makes it a matter of absolute necessity to subdivide the Linnean genera, which in fact, with regard to the majority of them, were theprimarygroups of his Orders, rather than an approximation to theultimate. But this principle may be carried too far: for it is the nature of man to pass from one extreme to the other: and this seems to me to be the case when it is proposed to make genera theextremeterm of subdivision before you arrive at species. But it is argued by a very acute Zoologist, that simplicity, perspicuity, and room for necessary variations are best preserved by distinguishing these subdivisions each by an appropriate name[1268]:—Granted. But still it is only a choice of evils. It would require probably more than 10,000 names to designate them, were every extreme group distinguished by a name: but if Mr. MacLeay's admirable pattern exhibited in his genusPhanæus[1269]were followed, it would not call for more than 2000—couldthe trifling difficulty occasioned sometimes by the discovery of a new group, be set against the advantage of having only 2000 names to commit to memory instead of 10,000[1270]? But if, after all, it is judged best to name subgenera, M. Savigny's excellent plan of distinguishing them by a plural termination would diminish the weight of the above objection, and might be used with advantage.
When the component parts of any minor group differ from another,—for the most part in important characters, indicating some tangible difference in their habits and economy, and confirmed by peculiarities in their larvæ; and these differences run through the whole, except that as usual they grow weaker as it is passing off to another; especially where they are striking in the centre or type of the group,—this is always a legitimate genus: but where the characters assumed are very slight, and nothing peculiar in its habits, economy or larva, warrant such distinction, it ought not to be conferred.
vii. I must next say a word concerning species and varieties. Aspeciesis a natural object whose differences from those most nearly related to it had their origin when it came from the hands of itsCreator; while those that characterize avariety, have been produced since that event. As we do not know the value and weight of the momenta by which climate, food, and other supposed fortuitous circumstances operate upon animal forms, we cannot point out any certain diagnostic by which in all cases a species may be distinguished froma variety;—for those characters that in some are constant, in others vary. In general, where there is no difference inform,appendagesandorgans,sculpture,proportionsandlarvæ,—colouralone, especially in insects inhabiting the same district, only indicates a casual variety. ThusAphodius luridushas sometimes pale elytra with the striæ black (Scarabæus nigro-sulcatusMarsh.): at others it has black spots between the striæ, as in the type: in a third variety the elytra are black at the base and pale at the apex (Sc. variusMarsh.); and lastly, in a fourth they are intirely black (Sc. gagatesMarsh.);—yet all these in every other respect precisely correspond. But the converse of this will scarcely hold good; for doubtless minor differences of structure are sometimes produced by a different food and climate: which may probably account for some variations observable in the individuals apparently of the same species obtained from different countries.
Having considered the kind and value of the groups into whichAnnuloseanimals, and more especially insects, may be divided, I shall next call your attention to theircomposition. There arefivenumbers and their multiples which seem more particularly to prevail in nature: namely,Two—Three—Four—FiveandSeven. But though these numbers areprevalent, no one of them can be deemeduniversal. Thebinarynumber, which affords the most simple, and for that reason perhaps not the least valuable, mode of arrangement, we see exemplified when two branches, so to speak, diverge from a common stem,—as in theVegetableandAnimalkingdoms; theterrestrialandaquaticPredaceous beetles;in thethalerophagousandsaprophagous Lamellicornones; in theAnopluraandThysanura; theChilopodaandChilognathaamongstApterousinsects; in theScorpionideaandAranideaamongst theArachnida; and in theMacruraandBrachyuraamongst the DecapodCrustacea. Again, in other casesthreeseems to be the most prominent number: this takes place sometimes with regard to theprimarygroups of an Order, or what I denominate theSuborders. Thus we have theDiurnal,Crepuscular, andNocturnal Lepidoptera[1271]; the Linnean generaBlatta,Mantis, andGryllusconstitute theOrthoptera; and other instances of this number might be produced in some minor groups. But that which appearsto prevail most widely in nature is what may be called thequaterno-quinary; according to which, groups consist of four minor ones; one of which is excessively capacious in comparison of the other three, and is always divisible into two; which givesfiveof the same degree, but of which, two have a greater affinity to each other than they have to the other three[1272]. Mr. W. S. MacLeay, in the progress of his inquiries to ascertain the station ofScarabæus sacer, discovered that the thalerophagous and saprophagous Petalocerous beetles resolved themselves each into a circle containingfivesuch groups. And having got this principle, and finding that this number and its multiples prevailed much in nature, he next applied it to the Animal Kingdom in general: and from the result of this investigation, it appeared to him that it was nearly, if not altogether, universal[1273]. Nearly at the same time a discovery almost parallel was made and recorded by three eminent Botanists, MM. Decandolle, Agardh, and Fries, with regard to some groups of the Vegetable Kingdom[1274]; and more recently Mr. Vigors thinks he has discovered the same quinary arrangement in various groups of birds[1275]. This isa most remarkable coincidence, and seems a strong argument in favour of Mr. MacLeay's system. I should observe, however, that according to that system, as stated in hisHoræ Entomologicæ, if the osculant or transition groups are included, the total number isseven[1276]:—these are groups small in number both of genera and species, that intervene between and connect the larger ones. Each of these osculant groups may be regarded as divided intotwoparts, the one belonging to theuppercircle and the other to thelower; so that each circle or larger group is resolvable into fiveinteriorand twoexteriorones, thus making up the numberseven. Though Mr. MacLeay regards this quinary arrangement of natural objects as very general, it does not appear that he looks upon it as absolutely universal,—since he states organized matter to begin in a dichotomy[1277]: and he does not resolve its ultimate groups into five species; nor am I certain that he regards the penultimate groups as invariably consisting of five ultimate ones. InCoprisI seem in my own cabinet to possess ten or twelve distinct types[1278]; and inPhanæus, the fifth type, which Mr. MacLeay regards as containing insects resembling all the other types[1279], appears to me rather divided intotwo; one formed byP. carnifex,Vindex,igneus, &c., and the other byP. splendidulus,floriger,Kirbii, &c.
The great point which demands our attention inconsidering a numerical arrangement of the Kingdoms of Nature is thevalueof the component members of each group. It is by no means difficult to divide aKingdom, aClass, or anOrderinto two, or three, or five, or seven or more groups, according to any system we may be inclined to favour; but it is not so easy to do this so that the groups shall be of equal rank. Yet it seems requisite that in grouping our objects, as we descend towards the lowest term we should resolve each only into its primary elements, and of them form the next group; and so on till we come to species. When I say ofequal rank, I do not mean an exact parity between the members into which a group is primarily resolvable,—because there will always be a degradationin descensufrom the perfection of the type; but merely that parity (to use a metaphor) that there is between children of the same mother, differing in their relative ages and approach to the perfection of their nature. Perhaps it may be observed with respect to the quinary system, that this condition is not complied with, since two of the groups takenper seappear really to form one group; or to be much nearer to each other than to the remaining groups. But when it is taken into consideration that this great group, always resolvable into two, is the typical group, and that the two are really equal, or rather superior in value to the three others, the objection seems to vanish.
With regard to all numerical systems we may observe, that since variation is certainly one of the most universal laws of nature, we may conclude that different numbers prevail in different departments, and that all the numbers above stated as prevalent are often resolvable or reducible into each other. So that where Physiologistsappear to differ, or think they differ, they frequently really agree.
II. TheAlmighty Creator, when he clothed the world that he had made withplants, and peopled it withanimals, besides the manifestation of his own glory, appears to have hadtwomost important purposes in view;—the one to provide a supply for the mutual wants of the various living objects he had created, for the continuance of the species, and for the maintenance of a due proportion, as to numbers, of each kind, so that all might subserve to the good of the whole; and the other, that by them he mightinstructhis creature man in such civil, physical, moral and spiritual truths, as were calculated to fit him for his station in the visible world, and gradually prepare him to become an inhabitant of that invisible one for which he was destined. The first of these purposes was best promoted by creating things "according to their kind," with sexes monœcious or diœcious; that groups of beings related to each other, and agreeing in their general structure, might discharge a common function. This we see to be the case generally in nature; for where there is an affinity in thestructure, there is usually an affinity in thefunction. The last,—or the instruction of man in his primeval state of integrity and purity,—was best secured by placing before him for his scrutiny a book of emblems or symbols, in which one thing either by its form or qualities, or both, might represent another. If he was informed by his Creator that the works of creation constituted such a book, by the right interpretation of which he might arrive at spiritual verities as well as natural knowledge,curiosity and the desire of information concerning these high and important subjects would stimulate him to the study of the mystic volume placed before him; in the progress of which he would doubtless be assisted by thatDivineguidance, which even now is with those who honestly seek the truth. Both divines and philosophers have embraced this opinion, which is built upon the word ofGoditself[1280].
This last purpose of the Creator was the root of the analogies, connecting different objects with each other that have no real affinity, observable in the works of creation: so that from the bottom to the top of the scale of being, there is many a series of analogous forms, as well as of concatenated ones; and the intire system of nature isrepresentative, as well as operative: it is a kind ofJanus bifrons, which requires to be studied in two aspects looking different ways. To what degree of knowledge the primeval races of men attained after the fall, by the contemplation and study of this book of nature, we are no where informed; but we learn from the highest authority that the revelation thatGodthus made of himself was in time corrupted, by those thatprofessingthemselves to bewisebecamefools, to the grossest idolatry, which sunk men in the lowest depths of sensuality, vice, and wickedness[1281].
In no country was this effect more lamentably striking than in Egypt, whose gods were all selected from the animal and vegetable kingdoms.
"Who knows not to what monstrous gods, my friend,The mad inhabitants of Egypt bend?The snake-devouring ibis these inshrine,Those think the crocodile alone divine;Others where Thebes' vast ruins strew the ground,And shatter'd Memnon yields a magic sound,Set up a glittering brute of uncouth shape,And bow before the image of an ape!Thousands regard the hound with holy fear,Not one Diana:—and 'tis dangerous hereTo violate an onion, or to stainThe sanctity of leeks with tooth profane.O holy nations, in whose gardens growSuch deities!"Juv.
"Who knows not to what monstrous gods, my friend,The mad inhabitants of Egypt bend?The snake-devouring ibis these inshrine,Those think the crocodile alone divine;Others where Thebes' vast ruins strew the ground,And shatter'd Memnon yields a magic sound,Set up a glittering brute of uncouth shape,And bow before the image of an ape!Thousands regard the hound with holy fear,Not one Diana:—and 'tis dangerous hereTo violate an onion, or to stainThe sanctity of leeks with tooth profane.O holy nations, in whose gardens growSuch deities!"Juv.
This species of idolatry doubtless originally resulted from their having been taught that thingsinnature were symbols of thingsabovenature, and of the attributes and glory of the Godhead. In process of time, while the corruptionremained, the knowledge which had been thus abused waslostor dimly seen. The Egyptian priesthood perhaps retained some remains of it; but by them it was made an esoteric doctrine, not to be communicated to the profane vulgar, who were suffered to regard the various objects of their superstitious veneration, not assymbols, but as possessed of aninherentdivinity: and probably the mysteries of Isis in Egypt, and of Ceres at Eleusis, were instituted, that this esoteric doctrine, which was to be kept secret and sacred from the common people, might not be lost.
But this kind of analogy is of a higher order than that of which I am here principally to speak,—that, namely,which the various objects of nature bear to each other. This, however, though of a lower rank, is essentially connected with the other, and leads to it; for it establishes the principle, that created things are representative or symbolical: and we find, when we view them in this light, that as we ascend from the lowest beings in the scale of creation, we are led from one to another till we reach the summit or centre of the whole, and are thus conducted to the boundaries of this visible and material system; from whence we may conclude that we ought not here to stop, but go on to something invisible and extra-mundane, as the ultimate object intended to be reflected from this great speculum of creation—theCreatorhimself, and all those spirits, virtues, and powers that have emanated from him.
Theanalogieswhich the various objects of the animal kingdom mutually exhibit, have for the most part been either overlooked by modern Physiologists, or have been mistaken for characters that indicateaffinity; a circumstance that has often perplexed or disrupted their systems. Dr. Virey appears to have been one of the first who obtained a general idea of the parallelism of animals in this respect[1282]; and M. Savigny has contrasted theMandibulataandHaustellataof the insect tribes as presenting analogies to each other[1283]. But a countryman of our own (often mentioned with honour in the course of our correspondence), peculiarly gifted by nature, and qualified by education and his line of study for such speculations, and possessing moreover the invaluableopportunity of consulting at his ease one of the first Entomological cabinets in Europe, in a work that will for ever couple his name with the science that he cultivates[1284],—has first taught the Naturalist the respective value and real distinctions of the two kinds of relationship that I am now discussing. He has opened to the philosopher, the moralist and the divine, that hitherto closed door by which our first parents and their immediate descendants entered the temple of nature, and studied the symbols of knowledge that were there presented to them: and in addition to his labours (in numerous respects successful), in endeavouring to trace out the natural groups of beings connected byaffinity, has pointed out how they illustrate each other byanalogy; thus affording, as was before observed[1285], a most triumphant reply to the arguments of those modern sophists, who, from the graduated scale of affinities observable in creation, were endeavouring to prove that animals, in the lapse of ages, were in fact their own creators[1286].
For the more satisfactory elucidation of the subject before us, I shall consider, first, how we are to distinguish affinities from analogies; and then mention some of the various instances of the latter that occur between insects and other animals, and between different tribes of insects themselves.
To know what characters denote affinity and what are merely analogical, it must be kept in mind that the former being predicated of beings in aseries(whether that series has its gyrations that return into themselves, or proceeds in a right line, or assumes any otherintermediate direction, it matters not), it cannot be satisfactorily ascertained but by considering attentively the gradual approximation or recession of the structure to or from a certain type in any point of such series. If, therefore, you wish to ascertain whether the characters, in which any given object resembles other objects in certain groups, indicate affinity or only analogy, you must first make yourself acquainted with the common features which distinguish the animals known to belong to that group,—either those relating to their structure, or to their habits and economy. If the object under your eye partakes in these characters more or less, in proportion as it approaches the type or recedes from it, the relation it exhibits is that ofaffinity; but if, though it resembles some members of it in several points of its structure, it differs from the whole group in the general features and characteristic marks that distinguish it, the relation it bears to those members is merely that ofanalogy. Thus, for instance,Ascalaphus italicusin its antennæ, the colouring of its wings, and its general aspect, exhibits a striking resemblance to abutterfly; yet a closer examination of its characters will satisfy any one that it is in quite a different series, and has noaffinitywhatever to that genus. A departure, however, in only one respect from what may be called thenormalcharacters of its group, does not annul the claim of any tribe of insects to remain in it; since this very often only indicates a retrocession from the type, and not a disruption of its ties of affinity. Thus the saw-flies (Serrifera) differ from the otherHymenoptera, though not in their pupæ, yet more or less in their larvæ; but this alone cannot countervail their agreement with that Order in their organs of manducationand motion, in their ovipositor, and in the other details of their structure[1287].
I have on a former occasion pointed out many of the analogies which take place between insects and other parts of the animal kingdom, and even between insects and the mineral and vegetable kingdoms[1288]: I shall now resume the subject more at large, but without recurring to those last mentioned. In considering the analogies which connect insects with other animals, or which they exhibit with respect to each other, we may have recourse totwomethods. We may either consider them as placed somewhere between the two extremes of a convolving series, from which station we may trace these analogiesupwardsanddownwardstowards each limit; or we may conceive them and other animals in this respect arranged in a number of series that areparallelto each other, in which the opposite points are analogous. The first mode will perhaps best explain the analogies that exist between insects and other animals, and the last those between different groups of insects themselves. I shall give an example or two of each method, beginning with the first.
There are two tribes in the animal kingdom that seem placed in contrast to each other, both by their habits and by their structure. One of these is carnivorous, living by rapine and bloodshed, and can seldom be rendered subservient to our domestic purposes; while the other is herbivorous or granivorous, is quiet in its habits, and easily domesticated. Amongst insects we find the representatives of both: those of the first tribe are distinguished by their predaceous habits, by the open attacks, or by the various snares and artifices which they employto entrap and destroy other insects. They may usually be known by their powerful jaws or instruments of suction; by their prominent or ferocious eyes; by the swiftness of their motions, either on the earth, in the air, or in the water; by their fraud and artifice in lying in wait for their prey. Amongst theColeoptera, the Predaceous beetles,—including the Linnean generaCicindela,Carabus[1289],Dytiscus, andGyrinus,—are of this description; and they symbolize those higher animals that by open violence attack and devour their prey:—for instance, the sharks, pikes, &c., amongst the fishes; the eagles, hawks, &c., amongst the birds; and the whole feline genus amongst the beasts. Similar characters give a similar relation of analogy to theMantidæandLibellulinaamongst theOrthopteraandNeuroptera. The whole family ofArachne, the larvæ of theMyrmeleonina, &c., portray those animals that to ferocity add cunning and stratagem, or suck the blood of their victims. TheMyriapodssymbolize in a striking manner the Ophidian reptiles. Look at anIulus, and both in its motions and form you will acknowledge that it represents alivingserpent; next turn your eyes to a centipede orScolopendra, and you will find it nearly an exact model of the skeleton of adeadone, the flat segments of its body resembling the vertebræ, its curving legs the ribs, and itsvenomous maxillæ the poison-fangs. The great body of theOrthoptera, theHomopterous Hemiptera, theLepidoptera, andTrichoptera, afford no example of Predaceous insects. All the analogies I have here particularized, ascending from the insect, terminate in races of a corresponding character and aspect amongst theMammalia, and thus lead us towardsmanhimself, or rather to men in whose minds those bad and malignant qualities prevail, which, when accompanied by power, harass and lay waste mankind; and thus ascending from symbol to symbol, we arrive at an animal who in his own person unites both matter and spirit, and is thus the member both of a visible and invisible world: and we are further instructed by these symbols,—perpetually recurring under different forms,—in the existence of evil and malignant spirits, whose object and delight is the corporeal and spiritual ruin of the noble creature who is placed at the head of the visible works ofGod.
The other tribe of animals that I mentioned of a milder character, may be looked upon as represented by many herbivorous, or not carnivorous, insects; amongst others, the Lamellicorn beetles imitate them by their remarkable horns, so that they wear the aspect of miniature bulls, or deer, or antelopes[1290], or rams, or goats, whether these horns are processes of the head or of the upper jaws. The gregariousHymenoptera, some of which form part of our domestic treasures, may be regarded in some degree as belonging to this department. From insects the ascent upwards, with regard toform, is by some of the branchiostegous fishes, which symbolize the horns ofcattle; with regard tocharacter, by the various species ofCyprinusand other similar genera.—Whether any of thereptilesmay be looked upon as falling into this division, I am not sufficiently conversant with them to assert; but if any, theChelonians, or tortoise and turtle tribes, are entitled to that distinction. Amongst the birds, theGallinæandAnseres,—from which Orders we derive our domestic poultry, whether terrestrial or aquatic,—and our game, form the step next below the ruminants, or cattle: and we are thus again led towards man, and are symbolically instructed in those domestic and social qualities which endear us to each other, best promote the general welfare, and render us most like good spirits and the Divinity himself; of whom the perpetual recurrence of animals exhibiting these amiable and useful qualities is calculated to impress upon us some notion. I might mention many more instances of ascending analogies; as from some of theDipteraby the parrots, to theQuadrumanesor monkey tribes—or from some of theIulidæthat roll themselves into a ball, to theArmadillo; but these are sufficient to set your mind at work upon the subject, so that you may trace them for yourself. Nor shall I occupy your time by pointing out how analogies may be traced from insects downwards towards the lowest term in the scale of animal life, but proceed to consider the analogies observable between insects themselves; in which I shall follow thesecondmethod lately mentioned, and consider them as arranged in parallel series.
In studying the analogies that take place between insects themselves, we should always bear in mind that our inquiry is not concerning anaffinitywhich demands a correspondence in various particulars that are not necessary to constitute an analogy; as, for instance, that thereshould be a mutual imitation in all the states of any two insects. Wherever we discover a marked resemblance between twoperfectinsects, there is a true analogy, though their metamorphosis may differ; and where there isnotthat resemblance, though the metamorphosis may agree, there is no analogy. In fact, insects are sometimes analogous in theirfirststate andnotin theirlast; and at other times analogous in theirlastandnotin theirfirst; but the analogy is most perfect when it holds inalltheir states: it then, indeed, almost approaches to an affinity. They may also be analogous to each other in theirhabitsandeconomy, when there is little or no resemblance in theirform; and,vice versa, be analogous in theirformand not in theirhabits. So that different sets of analogies may be assumed as foundations for different systems. Thus Mr. MacLeay assumes themetamorphosisas the basis of analogy between the corresponding Orders ofMandibulataandHaustellata[1291], while M. Savigny compares theperfectinsects[1292]: the result therefore differs in some instances. I shall now lay before you in a tabular view their plans and my own.
Savigny.
MacLeay.
In these two last columns, you see, I differ little from M. Savigny: I merely exclude theAphanipteraas forming an osculant Order, and I have added theColeopteraand HeteropterousHemipterafor reasons I shall soon assign. From Mr. MacLeay I differ more widely, which has resulted from our different ideas as to the mode of tracing analogies; his theory leading him to themetamorphosis, and mine leading me[1293]to theperfectinsect, for the foundation of our several systems. It remains that I show how each of the pairs in my columns represent each other: but I must observe, that the analogies exhibited by insects in the corresponding Orders of these columns are not equally striking in all their respective members; but only in certain individual species or genera, more or less numerous, by which the nearest approach is made to the contrasted forms.
To begin with theColeopteraand HeteropterousHemiptera.—Both are distinguished by having an ampleprothorax, a conspicuousscutellum, the neuration of their wings, the substance of the hard part of theirhemelytra, which, as inColeoptera, sometimes imitates horn and sometimes leather, and is occasionally, like elytra, lined with ahypoderma[1294]; the articulation of the head with the trunk is likewise the same in both[1295]: and some Heteropterous species so strikingly resemble beetles (Lygæus,brevipennis&c.), having little or no membrane at the end of their hemelytra, that they might easily be mistaken for them. These circumstances prove, I think, that this suborder is more analogous to theColeopterathan to theOrthoptera, with which it agrees in scarcely any respect but its metamorphosis. The counterparts of this last Order indeed, instead of theHeteropterous, are to be sought for amongst theHomopterous Hemiptera, various species of which exhibit a most marked and multifarious analogy with numerousOrthoptera. Many of both Orders (Cicada,Locusta), as you have heard long since, are signalized by possessing the same powers of song, and produced by an analogous organ[1296]: a large proportion also of both are endued with wonderful saltatorious powers, and their posterior tibiæ are similarly armed; their legs in general likewise are longitudinally angular, and the head in both articulates with the trunk in the same manner[1297]. In both Orders too, the upper organs of flight are most commonlytegmina, but sometimes in both they are nearly membranous, likewings. InCentrotusandAcrydium, the oneHomopterousand the otherOrthopterous, the front is bilobed, the eyes are small; there are only twostemmata between the eyes; the prothorax is conspicuous, and behind is producted into a long scutelliform process, under which all the parts also are analogous; the abdomen articulates with the trunk in the same way, is similar in shape in both, and consists of short inosculating segments. SomeFulgoridæandTruxalidesagree also in their producted front. Other analogous characters might be named between these tribes, but these are sufficient to confirm M. Savigny's opinion. That theNeuropterapresent analogies to theLepidoptera, though they differ so widely from them in their metamorphosis and habits, is evident from the instance lately adduced ofAscalaphus italicus, which was described as a butterfly by Scopoli[1298]; and many of theLibellulina, by their wings, partly transparent and partly opaque, and by the shape of those organs and of their bodies, imitate the Heliconian butterflies: and this resemblance is much more striking than any that occurs between the perfect insects in theNeuropteraand HomopterousHemiptera. With regard to theHymenopteraandDipterathe analogy is undisputed, and must strike every beholder; and one would almost say it was a real affinity, were it not that the resemblance is not only general between Order and Order, but that almost every Hymenopterous tribe has its counterpart amongst theDiptera; the saw-flies[1299]for instance, the ichneumons, the various false-wasps[1300], the false-bees[1301], the bees, the humble-bees, the ants, &c., severally find there a representative that wearsits livery and general aspect: a circumstance which evidently proves that it was part of the plan of theCreatorto place them in contrast with each other. Were I to pursue this subject further, it might not be difficult to show that were thetribesofMandibulataor ofHaustellataalso arranged in columns, analogies would be discoverable between their corresponding points: this seems to be Mr. MacLeay's opinion[1302]; and it is worth your pursuing the subject further, which cannot but prove very interesting.
But though the general analogy of these columns is that of Order to Order, yet individual species in each Order sometimes find their representatives in a different one from that with which they generally are contrasted;—thus someDiptera, asCulex, by the scales on the veins and other parts of their wings, are analogous toLepidopterarather thanHymenoptera[1303]; as is also the genusPsychodaby its form.
We come now to the consideration of a question not easy to be decided,—I mean, which Order of insects is to have theprecedency, and which is the connecting link that unites them to Vertebrate animals.
Linné (and Mr. MacLeay seems in this to coincide with him) considered theColeopteraas at the head of the Class of insects; De Geer thought theLepidopteraentitled to that honour; Latreille and Cuvier begin with theAptera: Marcel de Serres favours theOrthoptera[1304]; and others, on account of their admirable economy, have made theHymenopterathe princes of the insect world[1305].If the claim to priority was to be decided by the exquisiteness of instincts and the benefits conferred upon the human race, doubtless it would be in favour of the last-mentioned insects. If the power to do mischief carried it, and to lay waste the earth, theOrthopterawould be entitled as much as any to the bad pre-eminence. If beauty, and grace, and gaiety, and splendour of colours were the great requisite, and the law enjoined,Detur pulchriori,—theLepidopterawould doubtless win the throne. But if perfection and solidity of structure, as they ought, are to regulate this point; we must, I think, with the illustrious Swede, assign the palm to theColeoptera. If we consider these in all their parts, the organs for flight only excepted, they seem more perfectly formed and finished than the insects of any other order. But which of the Coleopterous tribes are entitled to the precedency? Linné placed the Lamellicorn beetles at the head of the order, beginning with theDynastidæ, probably led by some characters which seem to connect these with the Branchiostegous fishes. In this he was followed by Fabricius. But Latreille and most modern Entomologists have begun withCicindelaand the other Predaceous beetles. I am not certain what are Mr. MacLeay's sentiments on this subject; but from what he says in theAnnulosa Javanica[1306], it does not appear that he is a convert to the latter opinion. Bulk and strength seem the most striking characteristics of the former tribe, which represent the cattle or ruminants amongst Vertebrate animals.—Strength united with agility and a considerable portion of grace and symmetry evidently confersa degree of pre-eminence upon the latter, symbolizing the feline race, which seems to throw no small weight into their scale.
There are two Classes of Vertebrate animals with which insects may appear to claim kindred. Thefishes, and thereptiles.Fishesin their fins exhibit no small resemblance to insects; the pectoral and ventral ones representing their arms and legs, and the dorsal ones their wings:Pegasus Dracoin this last respect is not unlike a butterfly[1307]. In some genera (Ostracion,Pegasus, &c.), like insects the animal is covered with a hard shell or crust, formed by the union of its scales. The oralcirrhiof many fishes seem analogous to thepalpiof insects; and in some a pair longer than the rest represent theirantennæ[1308]. Another circumstance in which insects and fishes correspond, is the wonderful variety of forms, often in the greatest degree eccentric, that occurs in both Classes. Some of the cyclostomous fishes, asAmmocœtus,Gastrobranchus, are supposed to connect the fishes with theAnnulosa, by means of theAnnelidaas an osculant Class[1309], which Mr. MacLeay regards as the passage to theChilopoda[1310]: hisMandibulatahe considers as passing into theAnopluraby means of some osculant Order as yet unknown[1311]. But I must confess I can see no good ground for this last transition:—theAnopluraappear much more nearly related to thePsocidæ, especially by the apterousAtropos pulsatoria[1312]than to anyColeopterousinsect. But having stated these opinions, I shall leave you to draw your own conclusions, as the question is still perplexed with many difficulties. I am ready to admit that some Vertebrates approach near to theAnnelida; but that it is through them alone that they are connected with insects, is not at present clear.
With regard toreptiles, they seem to be connected with insects by several characters. In theChelonians, the skeleton merges in the external carapace or shell; theOphidianschange their skin like larvæ; theBatrachiansundergo metamorphoses; some of theSauriansalso have their changes: and theDraco volanshas wings somewhat analogous to those of insects[1313]. Were I to be asked what Order of insects could connect with reptiles, I should point to theOrthoptera, especiallyGryllusL., which by their noise and saltatorious powers not a little resemble frogs; and the larvæ of some strikingly imitate their form[1314]: and of others even that of a lizard[1315]. But these resemblances, after all, may only indicate analogies.