i

defect in his fyftem is, that the fourth clafs feparates from the third, animals of the fame kind, and which have a much greater resemblance to one another, than those of different kinds, that conftitute his third clafs. For while the third clafs is compofed of lepidopterous infects, of beetles and flies, animals exceedingly diftinct from one another, the fourth confifts only of flies which are not comprehended in the third. Thus, flies which are animals of one genus, are found feparated, and diftributed into different claffes, while butterflies and beetles, animals of different kinds, are found united in the fame clafs. This is certainly a very great defect, and it is further augmented, by Swammerdam's introducing into his fourth class, several flies, which, according to his own principles, ought naturally to have been ranged in the third.

Befides, as the state of chryfalis and nymph is, with infects, generally a state of weakness, and always of imperfection, and as moreover, it is the state under which they are the leaft known, and often with most difficulty found, because then they are for the most part enveloped in a cone, or hid in the earth, or in places where it is not eafy to find them. I am of opinion, that this state is not a proper one for furnishing fuch diftinctive marks as can be of any utility.

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III. Linnæus, in his Syftema Naturæ, divides infects into feven general claffes. In the firft clafs, he places all thofe which have covered wings, as the different forts of beetles in the fecond, thofe that have naked wings, fuch as butterflies, dragon-flies, ephemeræ, wafps, ichneumons, and other flies. In the third, thofe which he names half-winged, the character of which is, that they have not all wings, and have no covers to them: in this clafs he enumerates crickets, grafshoppers, ants, bugs, scorpicns. His fourth clafs comprehends infects that have no wings but limbs, as the loufe, the flea, the fpider, the lobfter, the onifcus, and the millepied. The fifth includes the creeping infects, whofe body is naked, and deftitute of limbs, as the tenia, the earthworm, the leech, the flug. The fixth contains both land and fea fhelled animals, and his seventh and last, such as he names zoophytes, furnished with limbs, fuch as the echinus, fepia, sea stars, &c.

[*As the fyftem here alluded to, was what Linnæus publifhed in the first edition of his Syftema Naturæ, and which

he

he afterwards changed for the beautiful fyftem, now almoft in general ufe, the editor thinks it needlefs to tranflate M, Lyonet's remarks on it. A general view of that improved fyilem, it may not be improper to give in this place.

Linnaeus was the firft who gave the proper definition of an infect, and that definition has been adopted by all fucceeding authors. Infects, according to him, in their per fect ftate, are animals with many feet, (i. e. more than four) breathing by means of lateral fpiracles, covered with an offeous cruft, instead of, fkin, and their heads furnifhed with moveable antenne, the organs of fome kind of fenfe. He divides the whole clafs of infects into feven orders. The first, containing all the infects that pafs with us, under the general name of beetles, he calls Coleoptera; thefe have four wings, the upper divided by a ftraight longitudinal future, hard, and ferving as cafes for the more tender, under-wings. The fe -cond, comprehending all infects of the bug kind, grasshoppers, &c. he calls Hemiptera; thefe have four wings, the two upper not fo hard as thofe of the former order, nor divided by a straight future, but lying over each other. The third includes butterflies, and moths; it is called Lepidoptera, from the fmall fcales which cover the wings. The fourth contains the dragon-flies, ephemere, &c. they have four membraneous and tranfparent wings, without any fting, and are called Neuroptera. The fifth includes bees, wafps, &c. which have likewife four membraneous wings, and are furnifhed with a fting; this order has the name of Hymenoptera. The fixth contains all forts of flies and infects with two wings only, and is thence called Diptera; and the feventh, containing fpiders, crabs, &c. is called Aptera, from their having no wings.]

IV. I come now to the divifion of our author; and I obferve, that if he had no other defign in this chapter, than to reduce to certain heads, the principal diversities in the forms of infects, nothing could hinder us from admitting his fyftem; but, if in place of this, his intention was to give us a general plan of the divifions of infects, to ferve as a rule to those who should propose to treat of them methodically, and to give their history compleat, I cannot enter into his ideas.

His first divifion diftinguishes infects into those with wings, and those without wings. But of what use is this divifion, when it is allowed, that infects in general, are pro

duced

duced from the egg without wings, and that it is not, till after having paffed the greater part of their lives in this ftate, that they acquire the power of flying? If the author understood, as Linnæus does, by infects without wings, fuch as never have any, and by thofe with wings, fuch as get them fooner or later, his divifion might be received; but this is not the cafe. He ranks among the infects without wings, thofe which having lived for a certain time without wings, acquire them afterwards, fuch as caterpillars, and various larvæ, which change into flies and beetles; fo that an infect which is placed in one of his general divifions to-day, may belong to the other to-morrow, which makes his fyf tem confufed, and more likely to lead to error, than to order.

He afterwards fubdivides unwinged infects into those which have legs, and those which have none. But this fe cond divifion has another defect, which we have taken notice of in two of the preceeding systems, to wit, that of including in one clafs, animals of very different appearance, while it diftributes into different claffes, animals of very fimilar forms. We fhall find, for example, the fnails which undergo no transformations, united with various forts of maggots, which are changed into flies, while thofe pfeudocaterpillars, which alfo change into flies, (i. e. tenthredos) are separated, and placed in the other divifion.

The author next diftributes unwinged infects with legs into different claffes, according to the number of their legs, but this divifion labours under the fame defect, that of feparating animals, that resemble one another, and of conjoining diffimilar ones. We fhall find, for example, caterpillars with fixteen, fourteen, twelve, and ten feet, although they all change into lepidopteræ, separated into fo many claffes, according to the number of their feet, while the caterpillar with ten feet, will be found included in the fame clafs with fome spiders, and those spiders will be feparated from those that have only eight feet, which laft, will, in their turn, be conjoined with mites and other animals, which have no refemblance to them in form. After having thus made fome fubordinate divifions of unwinged infects, the author goes on to thofe that have wings. Here he fucceeds better; but as infects, confidered before the time when, they receive their wings, have already been arranged by our author, un`der different claffes, which have no relation to those he af

figns them, after having acquired wings, a naturalift who proposed to follow M. Leffer's divifion, would find himfelf very much embarraffed, to conciliate the two forts of divifions of the fame infects fo oppofite to one another. He would be obliged to abandon one of them, unless he rather chofe to follow the injudicious manner of Johnfton, and to treat feparately of the fame animals, firft as creeping, and then as winged infects.

I hope thefe few remarks will be fufficient to fhew that many inconveniences would arife from adopting any of the four systems of infects, I have now mentioned.

fame time we cannot but be furprised to see a science which has been treated of, even fince the days of Ariftotle, make fo little progrefs, as never to have hitherto been properly fyftematiled. We would almoft be tempted to believe the thing impoffible, if it were not more reasonable to think that the defect proceeds from few people having given themfelves the trouble of reflecting on it. And this ought to induce all who study infects to turn their attention to the fubject, as a good fyftematic division is what the fcience ftands most in need of. The information which may be drawn from thofe authors who have not fucceeded will ferve to guide those who fhall undertake it after them. In order to make the attempt more easy, I have ventured to point out the faults of those fyftems which have been alrea dy devifed. The fmall experience I have in the matter, prevents me from entring the lifts myfelf; but if I were allowed to speak my own fentiments of the fubject I think that of all the general characters which diftinguifh infects, none is fo proper to furnish a first divifion as that remarkable difference, to wit that fome undergo transformations, and others always preferve the fame figure they had at first. This diverfity fuppofes in them a difpofition of organs, an internal structure, a mechanism so different that I believe nothing can more effentially diftinguifh them. According to this idea, then, we may arrange all infects into two claffes ; the first comprehending fuch as undergo no metamorpho fis; the second those which appear fucceffively under differént forms.

The first divifion thus eftablished would furnish a vast field for as many fubdivifions as the nature of the subject might require. I do not defign to detail thefe here, but fhall content myself with giving one example, following a

Lingle branch, by which I fhall defcend to a particular species among those that are best known.

The fecond clafs may be divided into two principal genera. The one will comprehend infects which undergo a partial external change of form; that is a change which is not so compleat but that there remain marks more or lefs diftinct of their former figure. The other will contain those whofe external change of form is fo total and compleat, that no traces of their former figure can be perceived. These last will be of three forts; infects which change into beetles, thofe which are transformed into flies, and those which become butterflies or moths. The infects

of this last fort will confift of caterpillars properly fo called and Spanners. (Geometræ) The Spanners will be either of a regular or of an irregular figure. The irregulars will be either those with twelve feet or those which depart from the cylindrical shape by turgefcences or protuberances, and thus of the reft.

Although I propose this firft idea of the general divifions as what appears to me the most natural and the moft practicable, it is not to be fuppofed that I give it as exempt from faults. I am perfuaded that difficulties will appear in every fyftem that can be formed. The author of nature, wishing as it were to fhew that he is above the laws and rules he hath himself established, feems fometimes defignedly to depart from them; hence it happens that however general the rules are on which a fyftem is founded, there will always be found exceptions which will render that system imperfect in proportion to their number. Sometimes thefe exceptions are of fo fingular a kind, that it is impoffible to forefee them, and nothing but experience can demonftrate them. Not to speak of any but fuch as I confider as difficulties in my own plan, who would suppose that among infects of the fame fpecies, and which is ftill more remarkable of the fame fex, there would be found fome who never change their form, and confequently belong to the first division, while others undergo a transformation, which by making them acquire wings, transfers them to the second divifion? This would appear fingular, and yet the aphides, infects in many respects remarkable, afford many examples of it. Who would think that there were infects, the females of which fuffer no transformation, while the male fuffers a total change of form? Of this however we find an example in the glowworm, the male of which is of the beetle kind, and the