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be afterwards changed for the beautisul system, now almost in general use, the editor thinks it needless to translate MLyonet's remarks on it. A general view of that improved system, it may not be improper to give in this place. • Linnæus was the sirst who gave the proper desinition of an insect, and that desinition has been adopted by all succeeding authors. Insects, according to him, in their persect state, are animals with many seet, (i. e. more than four) breathing by means of lateral spiracles, covered with an osseous crust, instead of ikin, and their heads surnished with, moveable amennæ, the organs of some kind of sense, He divides the whole class of insects into seven orders. The sirst, containing all the insects that pass with us, under the general Dame of beetles, he calls ColcopUra; these have four wings, the upper divided by a straight longitudinal suture, hard, and serving as cases for the more tender under-wings. The second, comprehending all insects of the bug kind, grasshoppers, &c. he calls Himiptera; these have sour wings, the two, upper not so hard as those of the former order, nor divided by a straight suture, but lying over each other. The third includes butterflies, and moths; it is called Lcpidoptera, from the small scales which cover the wings. The fourth contains the dragon-flies, ephemeræ, &c. they have four membraneous and transparent wings, without any sting, and are called Neuroptera. The fifth includes bees, wasps, &c. which have likewise four membraneous wings, and are surnished with a sting; this order has the name of Hymenoptera. The sixth contains all forts of flies and insects with two wings only, and is thence called Diptera; and the seventh, containing spiders, crabs, &c. is called Aptera, from their having no wings.]
IV. I come now to the division of our author \ and I observe, that if he had no other design in this chapter, than to reduce to certain heads, the principal diversities in the forms of insects, nothing could hinder us from admitting his system; but, if in place of this, his intention was to give us a general plan of the divisions of insects, to serve 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 sirst division distinguishes insects into those with wings, and thpsc without wings. But of what use is this division, when it is allowed, that insects in general, are pro
disced from the egg without wings, and (hat H is riot/ list after having passed the greater part of their lives in this state, that they acquire the power of flying? If the author understood, as Linnæus does, by insects without wings, such as never have any, and by those with wings, such as get them sooner or later, his division might be received; but this is not the cafe. He ranks among the insects without wings, those which having lived for a certain time without wings, acquire them afterwards, such as caterpillars, and various larvæ, which change into flies and beetles y so that an insect which is placed in one of his general divilions to-day, may belong to the other to-morrow, which makes his system confused, and more likely to lead to erfor, than to order.
He afterwards subdivides unwinged infects into those which have legs, and those which have none. But this second division has another defect, which we have taken notice of in two of the proceeding systems, to witj that of including m one class, animals of very different appearance, while it distributes into different classes, animals of very similar forms. We shall find, for example, the snails which undergo no transformations, united with various forts of maggots, which are changed into flies, while those pseudocaterpillars, which also change into flies, (i. e. tenthredos) are separated, and placed in the other division.
The author next dillributes unwinged insects with legs into dissererrt-crasses, according to the number of their legsj but this division labours under the fame defect, that of separating animals, that resemble one another, and of conjoining dissimilar ones. We shall find, for example, caterpillars with sixteen, fourteen, twelve, and ten feet, although they all change into lepidoptene, separated into so many classes, according to the number of their feet, while the caterpillar with ten seet, will be found included in the ftme class with some spiders, and those spiders will be separated from those that have only eight feet, which last, will, in their turn, be conjoined with mkes and other animals, which have no resemblance to them in form. After having thus made some subordinate divisions of unwinged insects, the author goes on to those that have wings. Here he succeeds better; but as insects, considered before the time when they receive their wings, have already been arranged by our author, under different classes, which have no relation to those he as- " -1 i
signs them, after having acquired wings, a naturalist who proposed to Follow M. Lester's division, would sind himself Very much embarrassed, to conciliate the two sorts of divisions of the fame insects so opposite to one another. He would be obliged to abandon one of them, unless he rather chose to follow the injudicious manner of Johnston, and to treat separately of the same animals, sirst as creeping, and then as winged insects.
I hope these sew remarks will be sussicient to shew that many inconveniences would arise from adopting any of the four systems of insects, I have now mentioned. At the seme time we cannot but be surprised to see a science which has been treated of, even since the days of Aristotle, make so littse progress, as never to have hitherto been properly systematised. . We would almost be tempted to believe the thing impossible, if it were not more reasonable to think that the desect proceeds from sew people having given themselves the trouble of reflecting on it. And this ought to induce all who study insects to turn their attention to the subject, as a good systematic -division is what the science stands most in need of. The insormation which may be drawn from those authors who have not succeeded will serve to guide those who shall undertake it after them. In order to make the attempt more easy, I have ventured to point out the faults of those systems which have been already devised. The small experience I have in the matter prevents me from entring the lists myself; but if I were allowed to speak my own sentiments of the subject I think that of all the general characters which distinguish insects, none is so proper to surnish a sirst division as that remarkable difference, to wit that some Undergo transformations, and others always preserve the same sigure they had at sirst. This diversity supposes in them a disposition of organs, an internal structure, a mechanism so different that I believe nothing can more essentially distinguish them. According to this idea, then, we may arrange all insects into two classes) the sirst Comprehending such as undergo no metamorphosis ; the second those which appear successively under different forms.
The sirst division thus established would surnish a vast sield for as many subdivisions as the nature of. the subject might require. I do not design to detail these here, but (hall content myself with giving one example, following a
single single branch, by which I shall descend to a particular species among those that are best known.
The second class 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 less distinct of their former figure. The other will contain those whose external change of form is so total and compleat, that no traces of their former figure can be perceived. These last will be of three sorts; infects which change into beetles, those which are transformed into flies, and those which become butterflies or moths. The insects of this last fort will consist of caterpillars properly so 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 Jepart from the .cylindrical shape by turgescences or protuberances, and thus of the test.
Although I propose this first idea of the general divisions as what appears to me the most natural and the most- practicable, it is not to be supposed that I give it as exempt from faults. I am persuaded that difficulties will appear in every system that can hi formed. The author of nature, wishing as it were to shew that he is above the laws and rules he hath himself establilhed, seems sometimes designedly to depart from them ; hence it happens that however general the tules are on which a system is founded, there will always be found exceptions which will render that system imperfect in proportion to their number. Sometimes these exceptions are of so singular a kind, that it is impossible to foresee them, and nothing but experience can demonstrate them. Not to speak of any but such as I consider as difficulties in my own plan, who would suppose that among insects of the fame species, and which is still more remarkable of the fame sex, there would be found some who never change their form, and consequently belong to the first division, while others undergo a transformation, which by making them acquire wings, transfers them to the second division? This would appear singular, and - yet the aphides, insects in. many respects remarkable, afford many examples of it. Who would think that there were insects, the females of which fuller no transformation, while the male suffers a total change of form ? Of this however we find an example in the glow.. vrczxa, the male of which is of the beetle kind, and the
R r female fjemale a creeping insect with six seet, which has scarcely any resemblance to it. It is likewise one of the most general ruks, that A\ proper caterpillars become butterflies or moths and yet among them we sind many species where the male alone turns into a persect insect of that kind, the female changing into a dull ill-stuped animal without wings. The rule is that all maggots subjact to a change are metamorphosed either into flies or beetles ; and yet the flea, though it springs from a maggot, is neither the one nor the other. The ant likewise comes from a maggot, and yet sew of thrm become winged. All these singularities are so many dissiculties which occur in the plan I have sketched, as they do in many instances in the systems of Swammcrdam, Linnaeus and Lesser ; but as dissiculties of this kind will alWays be unavoidable in every system which attempts a natural order, because the rules of that order however geneial they may be, are seldom universal; there is no other way but that of endeavouring to reconcile such dissiculties with the plan deviled. This may be done by assigning to insects of a doubisul class, th^t class in which the individuals are found, which are the most persect of their species; and to insects which belong properU to no division, that to which they have the nearest relation. Thus the winged aphides which srom tins circumstance are the most persect of their species, belong to the second general clasb in our system. According to my division, I would have no dissiculty in comprehending every species of aphis in this second class. Fcr the fame reason, the semale glow worm would be found among the beetles with their males, and the unwinged lepidopteræ, should be ranged in the fame class with the males; the winged ants would bring the whole species to the class cf. flies, and the relation which the flea has in many respects with beetles, would make it take its station at the end of the animals of that order. In this manner might dissiculties be obviated, and a methodical arrangement facilitated.
Page 43, 1. last.
the Gerdius. This is an aquatic worm. There are some terrestrial animals, which deserve ai. well as this to be called thread-worms. Caterpillars, nourish some of them in their intestines. I have seen some issue of disserent lengths from more than one species of caterpillars that seed on the alder. A caterpillar of the length of an in^h, surnished me witl^
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