Leffer gives the name of bag, to the pofterior extremity of thefe infects. PAGE 155, 1. 8. The papilla, from which they draw their threads. Spiders, which M. Leffer has here in view, have each, according to M. Reaumur, (Mem. de l'Academie de Sciences, 1713,) fix of these papillæ. The extremity of a papilla, in one of the house fpiders, when magnified by the microscope, appeared divided into an infinity of protuberances, fmaller, but difpofed much in the fame way, with thofe that occupy the cornea in the eyes of Mufcæ. Each protuberance or convexity, in this cafe, undoubtedly affords a different thread, or rather, it is probable, that each concavity, fituated between those convexities, is pierced by a hole, through which the thread iffues; the fmall elevations feem intended to prevent the threads from joining at their exit. These convexities are not fo apparent, at the extremities of the papillæ, in garden fpiders; but there is obfervable, a quantity of small hairs, which probably ferve the fame purpose, that is, to feparate the threads from one another. However this may be, it is certain, that of every teat in a spider, threads may be drawn from a thousand different places; fo that the fpider, having fix of thefe papillæ, has holes to allow a paffage to fix thousand different threads; and what is ftill more wonderful, these threads are already formed, when they arrive at the papillæ, and they have each its own little tract, which conducts it thither...Thefe little tracts are, moreover, inclosed in different fleshy tubes, which Reaumur fupposes to be equal in number to the papille; thefe tubes terminate in winding veffels, which he calls the great refervoirs, and of which there are three on each fide of the fpider; thefe three unite at a very long branch, which takes a ferpentine course,and after having formed feveral turns, each terminates in a veffel which has the form of a tear of glafs. These two veffels, are thofe which Reaumur confiders as the original fources of the threads of fpiders. Who could have imagi 'ned, that the formation of a spider's web required fuch apparatus; or, that the papillae of fo vile an animal, was an ob ject fo worthy of admiration! PAGE 155, 1. 16. A fort of horns. It is faid, that in fome infects, as for instance inftance, in the aphides, these horns are the organs of respiration. PAGE 156, 1. 3. *Forwards under the belly. As for inftance, in the large reddish yellow fpider, of which Frisch gives the history, (Aranea diadema.)-The Author. It appears from this note that the author is fpeaking of a particular species of fpider. That fpecies I have not had an opportunity of observing, but I have examined several other fpecies, and I can affirm, that I have found the male organs placed at the head, while thofe of the females were fituated in the belly, precisely in the fpot where Frifch pla ces those of the male in queftion. This would make me fufpect that the fpider he mentions was a female, and the more as he reprefents its body as exceedingly large, a property peculiar to the females of fpiders, for I have always found the males with an abdomen proportionally flender. Lyonet. PAGE 156, 1. 5. Situated as in the males. This is in general the cafe, but there are however fome exceptions. The inftance of the fpider mentioned in the preceding note is fufficient to fhew, that there are infects whofe male organs are placed differently from thofe of the female. PAGE 156, l. 10. Some likewife have a sting at the extremity. The author understands here by the word fting, not only that part which ferves as an inftrument of offence; but alfo that organ which ferves as a conduit to their eggs when they introduce them into bodies which for that purpose they need to pierce. As those parts are very different, it would be better to distinguish them by different names; that which ferves them for introducing their eggs, might be called the tail, (Cauda Lin.) and the term fting (Aculeus Lin.) appropriated to that which is properly fo. PAGE 157, 1. 3. Often more than half an inch in length. There are ichneumons in my collection with tails near two inches long, and furpaffing greatly the length of the infect itfelf. It is fel 3 D 2 dom dom that the tails of infects, which have any, terminate in a pointed knob. The greater part of them have a cylind rical form without any fenfible thicknefs at the extremity. PAGE 157, 1 25. *Thofe which depofite their eggs in other infects. Ichneumons depofite their eggs in the bodies of caterpillars where they are hatched, and produce larvæ; thefe larvæ maintain themfelves there, and feed on the fubftance of the caterpillars which thereby become weak and languifhing. When the larvæ have attained their fize, and neither find room nor food in the caterpillar, they make their way through its fkin and then the caterpillar dies. PAGE 157, 1. 31. They ufe it as a pike or lance. The fting is by no means an organ peculiar to the male infects. Among bees for inftance the males have no fting; it is the fame with wafps. The females only and the neuters are provided with it. PAGE 158, 1. first. Which they ufe as a fpiracle. There are fome aquatic infects which can elongate their tails to an aftonishing degree. The rat-tailed larvæ are well known, not indeed fo much by that name given them by Reaumur, as by the form of their tail. This organ, though longer than the animal, is only the cafe of another tail longer ftill, which is capable of great contraction, and enters into the body of the larva. This laft tail is the organ of its refpiration. It raises it, to the furface of the water to take in air, and while itself remains at the bottom, it can fend this tail to the furface tho the water fhould be nearly five inches deep; fo that it can extend its tail nearly five inches, a very confiderable length for an animal only feven or eight lines long. See Reaumur, Tom. IV. and Scottish Register, VOL. II. PAGE 158, 1. 12. * Larva that have their feet on the back. This is an obfervation of M. de Reaumur, as may be feen in the Mem. of the Royal Academy of Sciences, 1714, P. 103, and Frifch, P., N. 7. The author. I am not furprised that the author fhould advance fo po fitively that there is a particular class of infects both aqua tic and terreftrial, which before their transformation have their feet on the back; but which are no fooner divested of their fkin, and begin to fly, than they have their feet under the belly. Frifch in the place here quoted, expreffes himself on this head in a manner fo decifive, that it would appear incredulity to hefitate a moment in believing that there were fuch infects. Thefe are his words when fpeaking of the infect we fhall immediately mention. The greateft fingularity in this larva is, that it has its fix legs on its back. M. de Reaumur, in the Memoirs of the "Academy of Sciences, has well defcribed a fpecies of a "quatic larva, which has likewise its feet on the back; he, "fays he is uncertain under what division of infects to clafs ❝ it. For my part, I make a particular clafs of thefe infects, whether aquatic or terreftrial, that is, of those "infects which before their transformation, have their "feet upon the back. To this clafs, belongs the infect def"cribed by Reaumur, and the beetle in question. &c." Would not one imagine from this paffage that Frisch had difcovered a great number of infects of this kind, and that it only remained to clafs them? He cites however only these two species, and I do not remember that there is ano ther instance in his work. I do not mean to deny that there may perhaps be infects, that have at first their feet upon the back, and which, after their transformation, have them then under the belly; yet I think the circumftance very unlikely, and it has never hitherto occurred to me. It apa pears however, that Mr Frisch has been rather precipitate in establishing a clafs for fuch. M. de Reaumur does not affirm as a well afcertained fact, that the fingular infect which he defcribes in the Memoirs of the Academy, has actually its feet on its back. He fays only that it has them on the back, or on the oppofite fide to its belly, fuppofing the belly to be on that fide where the mouth and the anus are fituated, and towards which the head generally inclines. So that if this infect had accidentally its head and the anus placed a little differently from what is the ordinary position in infects, a circumftance not altogether fingular, it might, notwithstanding thefe appearances to the contrary, ftill have its feet on the fide oppofite to the back. Befides, neither Reaumur nor Frisch had feen the transformation of this animal, at least they do not mention their having feen it; and if they did not fee it, how could Frisch class this infect with those which, after their transformation, have the legs under the belly? How could he even affirm that it is among the number of those that undergo transformation? I come now to his own infect, which is the fingle one we can begin with in establishing this new clafs. I have examined this infect which is one of the largest found in this country, and confequently fo much the eafier examined. (It is the Dytifeus piceus Lin.) I have fed it, and followed it in its transformations from the egg to its becoming the perfect infect, which Frisch could not do, as he did not know its proper food; and the fruit I have reaped from my attention is, not only the discovery of many remarkable properties, but the pri vilege of affirming pofitively, and with more confidence than Frisch does the contrary, that the infect in question has, in every stage of its life, the legs placed in the under fide like all other infects. It would be fufficient to look at it fwiming to be convinced of this; but I have much more certain proofs; I have made the infects change into nymphs under my eye, and I have feen them very diftinctly in the act of withdrawing their feet from the cruftaceous cover under which they performed the office of feet, while the infects were ftill in a state of larva. This is not all; as I have brought up many, it has fometimes happened that when they were preparing themselves to appear in the state of nymph, fome of them have not been able to extricate their head from the old cranium: and therefore their skin burst on different parts of their body, without their being able to difengage themselves from the fragments. I have then taken them, and have removed the skin from the place oppofite to that where the feet of the infect were placed; here according to Frisch, the limbs of the nymph ought neceffarily to have been found, but I never found there any thing refembling them; afterwards I difengaged the head from the old cranium, but when I attempted to remove the skin from the place where the feet were fituated in its larva state, I never could fucceed, the feet of the nymph being there entangled in the cruftaceous cover of thofe of the infect; that cover ferved them as a fheath, and to it they were attached fo ftrongly that I could not difengage them without their breaking. I had thus a nymph which had its fix feet broken off, and of which the part torn away, remained in the crustaceous cover of the feet of the infect. Can there be a stronger proof that this animal in its creeping ftate, has its feet precifely |