^338. 



THE INSECTA. 



42T 



convolutions. The colon is constantly of a large size, and is often dilated 

 into a caecum at its anterior portion/''^ 



Among the Aptera, the Nirmidae, Poduridae, and Lepismidae, have, at 

 the posterior extremity of the oesophagus, a kind of crop, which, with 

 Lepisma, is succeeded by a globular gizzard provided with six teeth. The 

 proper stomach has the form of a long tube, and is not flexuous as with the 

 Pediculidae. With these last, and with the Nirmidae, which are parasites, 

 it has, at its anterior extremity, two caeca directed forwards. But the 

 intestine which succeeds it, is very short with all the Aptera.*"-^ 



With all the hemimetabolic Insecta, or the Orthoptera and Hcmiptera, 

 the digestive canal of the larvae and pupae diifers but little from that of 

 the perfect insects. ^'^^^ With the Coleoptera, the larvae lilcewise resemble 

 the perfect insects in this respect, — their mode of life being generally the 

 same, as has already been evinced by the structure of their oral organs. 

 The stomach is usually shorter and larger, and the number of its appendages 

 less, than with the perfect forms. ^"^^ 



The larvae of the remaining holometabolic Insecta, which differ essentially 

 from the imagines as to their oral organs, beside living upon different food, 

 have also a digestive canal so different, that it must undergo a constant 

 and gradual change during the quiescent pupa state. ''""^ Most of these hirvae 

 have powerful masticatory organs, — such are those of the Lepidoptera, the 

 Tenthredinidae, the Siricidae, Phryganidae, Sialidae, and the cephalous 

 ones of the Culicidae and Tipulidae. The digestive canal here is straight 

 and rarely longer than the body ; its gi'eater portion consists of a large and 

 usually varicose stomach, while the ileum and colon are pretty short. With 

 the larvae of the Lepidoptera, the cylindrical ileum is large and divided 

 into six lateral pouches, by as many longitudinal septa. '■'^''* But with the 

 cephalous larvae of the Mycetophilidae and Sciaridae, and the acephalous 

 ones of the Diptera, the digestive canal is formed upon a wholly different 



31 Tliis caecum is found with Hipparchia, Port- 

 tia, Sphinx, Gastropacha, Euprepia, Acidalia, 

 Cabera, Adela, Chilo, and Tinea. It is wanting 

 with Vanessa, Zygaena, Hepiolus, Cossus, Ypo- 

 nomeuta, and Pterophorus. 



'i'i See Ifitzsch, in Germar''s Magaz. d. Entom. 

 III. p. 280 (Nu-midae) ; Nicolet, loc. cit. p. 46, 

 Pi. IV. fig. 2 (Poduridae) ; Swammerdamm, Bib. 

 der Nat. p. 33, Taf. II. fig. 3 ; Ramdohr, loc. cit. p. 

 185, Taf. XVI. fig. 3, and Taf. XXV. fig. 4, and 

 Treviranus, Verm. Schrift. II. p. 13, Taf. UI. fig. 

 1-6 {Pediculus and Lepisma). 



33 See Suckow, in Heusinger^s Zeitsch. II. Taf. 

 I. fig. 8 (Aeschna), and Rathki, in MiUler^s 

 Arch. 1844, p. 35, Taf. II. fig. 4 (Gryllotalpa). 



34 With the larvae of Calosoina, the stomach is 

 straight and without caeca (Burrneister, Trans, of 

 the Entom. Soc. I. p. 236, PI. XXIV. fig. 10, 11). 



With Hydrophilus piceus, a.nd Dytiscus mar- 

 ginalis, it is varicose, slightly tortuous, and with- 

 out caeca {Suckow, in Heusinger's Zeitsch. II. 

 Taf. IV. fig. 26, and Burmeister, Handb. I. Taf. 

 X. fig. 3). The larvae of the Lampyridae, Pyrochro- 

 idae, Mordellidae, and CurcuUonidae, differ but 

 little from the imagines as to their digestive canal 

 iL. Dufour, Ann. d. Sc. Nat. III. 1824, PI. XI. fig. 

 7 {Lampyris) ; Ibid. XIII. 1840, PI. V. fig. 5 

 (Pyrockroa); XIV. 1840, PI. XI. fig. 9 (JV/or- 

 della) ; and Burmeister, Ziir Naturg. d. Calandra, 

 p. 8, fig. 3.) The most marked difference between 

 the larvae and the imagines, is observed with the 

 Lamellicornes. The first have a very spacious. 



straight stomach, which, at both extremities and , 

 sometimes also in the middle, has a circle of simple 

 or varicose, thickly-set caeca ; the ileum is very 

 short, and the large intestine extremely large and! 

 always bent forwards ; see Roesel, Insektenbelust- 

 II. Taf. VIII. IX.; Suckow, loc. cit. III. Taf. III. 

 fig. 87 {Melolontha) > L. Dufour, Ann. d. Sc. 

 Nat. XVIII. 1842, PI. IV. fig. 8, PI. V. fig. 18. 

 (Cetonia and Dorcus) ; finally, the excellent work 

 of De Haan, Sur les mitamorphoses des CoUl'op- 

 tires, Mem. I. les Lamellicornes, in the Nouv. Ann. 

 du Mus. IV. 1835, p. 153, PI. XVI.-XIX. 



35 For this metamorphosis of the intestinal canal, 

 see Dutrochet, Jour, de Physique, &c., LXXXVI. 

 1818, p. 130, or MeckeVs deutsch. Archiv IV. p. 

 285, Taf. III. (Bombyx, Myrmeleon, Apis, Polls- 

 tes, Tenthredo and Eristalis). This metamor- 

 phosis with Sarcophaga haemorrhoidalis has 

 been described and figured by L. Dufour, Mem. 

 präsentes, &c., IX. p. 580, PI. III. 



3« See Swammerdamm, Bib. ■ der Nat. Taf. 

 XX.XIV. fig. 4 ; Lyonet, Traite, &c., PI. XIII. ; 

 Ramdohr, loc. »cit. Taf. XVIII. fig. 5. Many 

 naturalists have carefully observed the metamor- 

 phoses of the digestive canal with the Lepidoptera j 

 see Herold, Entwickelungsgeschichte d. Schmetterl. 

 Taf. III. fig. 1-12 (Pontia brassicae) ; Suckow, 

 Anat. physiol. Untersuch, p. 24, Taf. II. fig. 1-10 

 {Gastropacha pini) ; and Newport, Philos. Trans. 

 1834, PI. XIV. fig. 11-13 {Sphinx ligustri)^ 

 This last author has figured the digestive canal t». 

 situ in all the three states. 



