INSECTS. 



Joint is very clearly exemplified this family. Tlie larvse 

 of all the genera', whi h compofe it, have a large and fliort 

 alimentary canal, divided into the following parts, i. A 

 ^lort and we?.k. ocfophagiis. 2. A llraight cylindrical fto- 

 ir.ach, tokrably thick and mufcular, furrounded by three 

 circles of fmall cxca, placed, one at the commencement, one 

 at tlie middle, and the third at the end of the cylinder. Thefe 

 ca;c:l arc numerous, weak, and fliort : thofc of the third cir- 

 cle are ramified in the larvK of the fcarabrei properly fo 

 called (les geotrupes of Latrcille). In the mclolonths the 

 ceca of the firll circle have fmall lateral denticulations, 

 which may be regarded as fo many fmaller cica. The upper 

 a:!d lower circle in the lucani are compofed of a fmall number 

 of large crcca, while the middle is made up of very numerous 

 fmall ones. Probably they all fecrete and pour into the ito- 

 mach fome diffolving fluid. 3. A fliort intefl:ine of much 

 thiimer fides, and rather fliortcr in length than the ftomach. 

 Its origin, which is rather expanded, receives above the he- 

 patic vefiels ; it terminates at the pollerior extremity of the 

 body of the larva. 4. An enormous colon, or large inteftine, 

 three times as large as the ftomach, and filling all the pof- 

 terior third of the body. It pofiefles two fmooth bands, 

 between which are tranfverfe folds, producing a cellular ap- 

 pearance like that of the human colon. Its courfe is in a direc- 

 tion contrary to that of the fmall inteftine ; that is, it returns 

 from behind forwards, and lies upon that inteftine. J. A 

 rcftum turning from before backwards upon the colon, in 

 order to terminate at the anus. It is flender and ftraight, 

 without any inequality. 



We fliould have expeftcd that the perfeft infeft would 

 retain fome trace of fuch fl:rongly marked peculiari; ies ; yet 

 there is really no veftige of them difcernible. All thefe in- 

 fecis, lucani, fcarabxi, melolonthi, cetonix, have a long 

 flender canal, four or five times longer than the body, very 

 much convoluted, and pofiefling hardly any dilatation. Some- 

 times the anterior portion is merely a little larger and folded 

 tranfverfely. 



2. In the cpleoptera carnivora. As the habits of thefe 

 animals are very different from thofe of the preceding, tlieir 

 alimentary canal is different in both ftates. In the perfedl 

 ftate it confifts, of, ift, a long and very dilatable ocfopha- 

 gus. 2. A firil ftomach, nearly fpherical in its fiiape, with 

 mufcular parietes and tranfverfe wrinkles. 3. A fecond fto- 

 mach, membranous, elongated, and villous; not on the infide, 

 as thofe of certain vertebral animals are, but on the outfide. 

 The villi are veffels which draw, from the furrounding 

 nutrient fluid, the gaftric juice which they pour into the 

 ftomach, according to the laws of fecretion in infefts ; con- 

 fidered as animals which have no circulating organs. 4. An 

 inteftine of moderate length, between once and twice the 

 length of the body, fn-.all and uniform in its diameter 

 throughout. 5. A conical and rather long cxcum inferted 

 near the anus. Near the margin of the anus are found two 

 veficl^s, which fecrcle the acrid fluid almoft conttantly voided 

 by thefe animals when they are feized. 



Such is the ftruAure of the genera feparated from the 

 carabi, the cicindelx, and the dytifci : their larvae have no 

 dilatation like a ftomach ; their canal is fmall, all of one 

 lize from the mouth to the anus, and about one-half longer 

 than the body. A cscum, however, may be obfervcd near 

 the anus in the larvx of the dytifci. 



3. In the coleoptera clavicornia. The hydrophilus 

 piceus, in its perfetl ftate, has very long cylindrical intef- 

 tines (four or five times longer than the body), uniform in 

 fi/e throughout, and forming large convolutions in the ab- 

 donicn. 'J'iie larva, which is much more carnivorous, has 

 •ftort inteftines (half as long again as the body), of which 



nearly two-thirds form an elongated ftomach, villous exter- 

 nally ; the reft is fmootii, and divided by a contraction into 

 two parts. The filphx, on the contrary, have in their perfedl 

 ftate fucli a ftomach, followed by a fmall inteftine twice as 

 long as the body. 



4. In the coleoptera lignivora. The larvx of the prioni and 

 cerambyces have very large inteftines, with their fides nearly 

 uniform throughout, and forming four folds, each of which 

 is as long as the body. The commencement, which alone 

 can be compared to a ftomach, is rather corrugated tranf- 

 verfely like a colon. The perfefl infedl has firft a membra- 

 nous and round ftomach, then an oval one, which is infenfibly 

 contracted into a cyhndrical canal, fndden'y growing 

 fmaller at the infertion of the hepatic veffels, and continuing 

 fa to tl-.o anus. Tlie whole canal is at raoft twice as long as 

 the body. 



The larva of the lamia. Fab. has firft a very diftinft fto- 

 mach, then a knotted fmali inteftine, which is fuddenly 

 changed into a large inteftine longer than itfelf. 



5. In the coleoptera filicornia, of the family of the vefi- 

 cantix, the meloe poffeffes an enormous oval ftomach, filling 

 nearly the whole abdomen. The front is covered with 

 ftrong circular fibres ; and a cylindrical valve, analogous 

 to the valvula coli of man, is obferved at the cordia. 



In the tamily of the lacifuga, the tenebrio has a cylindri- 

 cal elongated ftomach, a firft inteftine, which is rather flen- 

 der, and another fomewhat larger. The whole canal is 

 about three times the length of the body. The blaps has a 

 mufcular cylindrical ftomach, another equalV large but 

 membranous, feparated from the former by a flight conftric- 

 tion, and a fmall inteftine which is a httle enlarged towards 

 the anus. The proportionate length of the whole is about 

 the fame as in the lall inftance. 



6. The brachelytra, or ftaphylini, refemble the carnivora 

 in the villofity of the tlomach, as they do in their habits. 



II. In the Orthoptera. — Thefe, in the clafs of infects, 

 feem analogous to tiie ruminants among the quadrupeds, at 

 Icaft in refpeft to the complication of tlie ftomach, and fome 

 fuppofe that their aliment may be feen brought back into the 

 mouth for the purpofe of a fecond maftication. As they 

 undergo an imperfect; nietamorphofis, their ahmentary 

 canal is the fame in the larva as in the perfeft ftate. It 

 confifts in general of the following parts, i. An oefophj;* 

 gus of the ufual kind. 2. A firft membranous ftomach. 

 In moft genera this is a firaple dilatation of the ocfophagus, 

 of which the internal membrane is fmooth and folded longi- 

 tudinally. In the locufta it is rather, and in the blatta con- 

 fiderably larger than in the other genera. In the acheta it is 

 an oval bag, having quite a lateral pofition, connefted to the 

 fide of the ocfophagus like a cxcum, with one opening for 

 the reception and diicharge oi its contents. 3. A fecond 

 ftomach or gizzard, fmall, nearly round, poffeiiing a very 

 thick mufcular coat, and armed internally with fcales or teeth. 

 In the locufta and acheta thefe are longitudinal rows of fine 

 and numerous fcales, placed one over the other like the tiles 

 of a roof, and direded backwards. In the blattx there is a 

 fingle row of fix or eight large curved teeth, denticulated 

 like the bills of birds of prey, and direfted backwards, 

 4. The cxca or third ftomachs are immediately round the 

 pofterior orifice of the gizzard, and vary in number. The 

 locufta and acheta have two large ones, and this has given rife 

 to the remark that the grylli have four ftomachs like the ru- 

 minating mammaha The internal membrane is much folded, 

 and its extremity receives many fmall fecretory veffels, which 

 pour out gaftric juice. There are five of thefe cxca in the 

 gryllus, and eight or ten in the blattx. 5. The inteftinal 

 canal varying in length and diameter. 



Z2 The 



