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

Linnæus 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 of feous cruft, instead of skin, and their heads furnished with moveable antennæ, the organs of fome kind of fenfe. He divides the whole clafs of infects into seven orders. The firft, containing all the infects that pafs with us, under the general name of beetles, he calls Coleoptera; these have four wings, the upper divided by a straight longitudinal future, hard, and ferving as cafes for the more tender under-wings. The fecond, 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 small 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 furnished 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 ob serve, that if he had no other design in this chapter, than to reduce to certain heads, the principal diverfities 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 propofe 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 ufe 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, fuck 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, those 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 confused, and more likely to lead to error, than to or

der.

He afterwards fubdivides unwinged infects into those which have legs, and those which have none. But this fecond 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 those pfeudocaterpillars, which also change into flies, (i. e. tenthredos) are feparated, and placed in the other division.

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 separating animals, that refemble 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 lepidoptera, 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 fpiders, and thofe fpiders 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 those 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, under different claffes, which have no relation to those he af

figns them, after having acquired wings, a naturalift wha proposed to follow M. Leffer's divifion, would find himself 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, unlefs he rather thofe to follow the injudicious manner of Johnston, 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 fyftems of infects, I have now mentioned. At the fame time we cannot but be surprised 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 fyftematifed.. 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 ftudy infects to turn their attention to the fubject, as a good fyftematic divifion is what the fcience ftands moft in need of. The information which may be drawn from thofe authors who have not fucceeded will ferve to guide those who shall undertake it after them. In order to make the attempt more eafy, I have ventured to point out the faults of thofe fyftems which have been alrea dy devised. 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 diftinguish 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 diversity fuppofes in them a difpofition of organs, an internal structure, a mechanism fo different that I believe no thing can more effentially diftinguish them. According to this idea, then, we may arrange all infects into two claffes; the first comprehending fuch as undergo no metamorphofis; the fecond thofe which appear fucceffively under differ ent forms.

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

fingle branch, by which I fhall defcend to a particular fpecies 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 fo compleat but that there remain marks more or lefs diftinct of their former figure. The other

will contain thofe whofe external change of form is fo total and compleat, that no traces of their former figure can be perceived. Thefe laft will be of three forts; infects which change into beetles, thofe which are transformed into flies, and thofe 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 thofe with twelve feet or those which depart from the cylindrical shape by turgefcences or protuberances, and thus of the rest.

Although I propofe this firft idea of the general divifions as what appears to me the most natural and the most 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 bath 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 fyftem imperfect in proportion to their number. Sometimes thefe exceptions are of fo fingular a kind, that it is impoffible to foresee 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 fuppofe 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 divifion, while others undergo a transformation, which by making them acquire wings, transfers them to the fecond divifion? This would appear fingular, and yet the aphides, infects in many refpects 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

Rr

female

female a creeping infect with fix feet, which has fcarcely any resemblance to it. It is likewife one of the moft general rules, that all proper caterpillars become butterflies or moths and yet among them we find many fpecies where the male alone turns into a perfect infect of that kind, the female changing into a dull ill-fhaped animal without wings. The rule is that all maggots fubject to a change are metamorphofed either into flies or beetles; and yet the flea, though it fprings from a maggot, is neither the one nor the other. The ant likewife comes from a maggot, and yet few of them become winged. All thefe fingularities are so many difficulties which occur in the plan I have sketched, as they do in many inftances in the fyftems of Swammerdam, Linpaeus and Leffer; but as difficulties of this kind will always be unavoidable in every fyftem which attempts a natural order, because the rules of that order however general they may be, are feldom univerfal; there is no other way but that of endeavouring to reconcile fuch difficulties with the plan devifed. This may be done by affigning to infects of a doubtful clafs, that clafs in which the individuals are found, which are the most perfect of their species; and to infects which belong properly to no divifion, that to which they have the nearest relation. Thus the winged aphides which from this circumftance are the most perfect of their fpecies, belong to the fecond general clafs in our fystem. According to my divifior, I would have no difficulty in comprehending every fpecies of aphis in this fecond clafs, For the fame reason, the female glow worm would be found among the beetles with their males, and the unwinged lepidopteræ, fhould be ranged in the fame clafs with the males; the winged ants would bring the whole fpecies to the clafs of flies, and the relation which the flea has in many refpects with beetles, would make it take its station at the end of the animals of that order. In this manner might difficul ties be obviated, and a methodical arrangement facilitated.

PAGE 43, 1. laft.

The Gordius. This is an aquatic worm. There are fome terreftrial animals, which deferve as well as this to be called thread-worms. Caterpillars nourish fome of them in their inteftines. I have feen fome iffue of different lengths from more than one fpecies of caterpillars that feed on the alder. A caterpillar of the length of an inoh, furnished me with

ona