•§> 338. THE INSECTA. 427 



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 

 Leplsma, 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 heraimetabolic Insecta, or the Orthoptera and Hemiptera, 

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

 the perfect insects. <'^'^' With the Coleoptera, the larvae likewise 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 larvae 

 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 greater 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 This caecum is found with Hipparchia, Port- straight stomach, which, at both extremities and 

 tia, Sphinx, Gastropacha, Eiiprepia, Acidalia, sometimes also in tlie middle, has a circle of simple 

 Cabera, Adela, C/iilo, a,nd Tinea. It is wanting or varicose, thickly-set caeca; the ileum is very 

 with Vanf-ssa, Zygae.na, Hepiolus, Cossus, Ypo- short, and the large intestine extremely large and 

 nomeuta, and Pterophorus. always bent forwards ; see Roesel, Insektenbelust. 



32 See JVitzsch, in Gennar's Magaz. d. Entom. II. Taf. VIII. IX.; Suckow, loc. cit. III. Taf. III. 

 III. p. 230 (Nirmidae) ; Nico/et, loc. cit. p. 46, fig. 87 {Melolontha) , L. Dufour, Ann. d. Sc. 

 Vl. IV. fig. 2 (Poduridae) ; S uwnmerdamm , Bib. Nat. XVIII. 1842, PI. IV. fig. 8, PI. V. fig. 18 

 der Nat. p. 33, Taf II. fig. 3 ; Ramdohr, loc. cit. p. {Cetonia and Dorcus) ; finally, the excellent work 

 185, Taf. XVI. fig. 3, and Taf. XXV. fig. 4, and of De Haan, Sur les mBtamorphoses des Coleop- 

 Treviranas, Verm. Schrift. II. p. 13, Taf. III. fig. teres, Mem. I. les Lamellicornes, in the Nouv. Ann. 

 1-6 (Pediculus and Lepiama). du Mus. IV. 1835, p. 153, PI. XVI.-XIX. 



33 See Suckoili, in Heusinger\^ Zeitsch. II. Taf. 3.5 For this metamorphosis of the intestinal canal, 

 I. fig. 8 (Aeschna), and Rath/ce, in MuUer''s see TJuirocAei, Jour, de Physique, &c., LXXXVI. 

 Arch. 1844, p. 35, Taf II. fig. 4 (Gryl/otalpa). 1818, p. 130, or Meckel's deutsch. Archiv IV. p. 



34 With the larvae of Ca/o«o;/!a, the stomach is 285, Taf III. (Bombyx, Myrmeleon, Apis, Polis- 

 Btraight and without caeca {Burmeister, Trans, of tea, Tentltredo and Eristalis). This metamor- 

 the Entom. Soc. I. p. 236, PI. .XXIV. fig. 10, 11). phosis with Sarcophaga haemorrhoidalis has 



With Hydrophilus piceus, and Dytiscus Ttiar- been described and figured by L. Dufour, Mem. 



ginalis, it is varicose, slightly tortuous, and with- presentes, &c., IX. p. 580, PI. III. 



out caeca (Suckow, m Heusing-er's Zeitsch. II. 36 See Swammerdamm, Bib. der Nat. Taf. 



Taf IV. fig. 26, and Burmeister, Handb. I. Taf. XXXIV. fig. 4 ; Lyonet, Traite, &c., PI. Xni. ; 



X. fig. 3). ThelarvaeoftheLampyridae, Pyrochro- Ramdohr, loc. cit. Taf XVIII. fig. 5. Many 



idae, M'jrdeilidae, and Curculionidae, differ but naturalists have carefully observed the metamor- 



little from the imagines as to their digestive canal phoses of the digestive canal with the Lepidoptera; 



{L. Dufour, Ann. d. Sc. Nat. III. 1824, PI. XI. fig. see Herold, Entwickelungsgeschichte d. Schmetterl. 



1 {Lampyris) ; Ibid. XIII. 1840, PI. V. fig. 5 Taf III. fig. 1-12 (Pontia brassicae) ; Suckow, 



(Pyrochroa) ; XIV. 1840, PI. XI. fig. 9 (Mor- Anat. physiol. Untersuch. p. 24, Taf II. fig. 1-10 



della) ; and Burmeister, Zur Natm-g. d. Calandra, (Gastropacha pini) ; and Newport, Philos. Trans. 



p. 8, fig. 3.) The most markwl difference between 1834, PI. XIV. fig. 11-13 (Sphinx ligustri). 



the larvae and the imagines, is observed with the This last author has figured the digestive canal in 



Lamellicornes. The first have a very spacious, sita in all the three states. 



