$ 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 cesophagus, 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 Hemiptera, 
the digestive canal of the Jarvae 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 
81 This caecum is found with Hipparchia, Pon- 
tia, Sphinx, Gastropacha, Euprepia, Acidalia, 
Cabera, Adela, Chilo, and Tinea. Itis wanting 
with Vanessa, Zygaena, Hepiolus, Cossus, Ypo- 
nomeuta, and Pterophorus. 
See Nitzsch, in Germar’s Magaz. ad. Entom. 
III. p. 280 (Nirmidae) ; Nicolet, loc. cit. p. 46, 
PL IV. fig. 2 (Poduridae) ; Swammerdamm, Bib. 
der Nat. p. 33, Taf. IL. fig. 3; Ramdohr, loc. cit. p. 
185, Taf. XVI. fig. 3, and Taf. XXV. fig. 4, and 
Treviranus, Verm. Schrift. II. p. 13, Taf. III. fig. 
1-6 (Pediculus and Lepisma). 
83 See Suckow, in Heusinger’s Zeitsch. II. Taf. 
I. fig. 8 (deschna), and Rathké, in Muiller’s 
Arch. 1844, p. 35, Taf. II. fig. 4 (Gryllotalpa). 
84 With the larvae of Calosoma, the stomach is 
straight and without caeca (Burmeister, Trans. of 
the Entom. Soc. I. p. 236, Pl. XXIV. fig. 10, 11). 
With Hydrophilus piceus, and Dytiscus mar- 
ginalis, it is varicose, slightly tortuous, and with- 
out caeca (Suckow, in Heusinger’s Zeitsch. IT. 
Taf. IV. fig. 26, and Burmeister, Handb. I. Taf. 
X. fig. 3). The larvae of the Lampyridae, Pyrochro- 
Ydae, Mordellidae, and Curculionidae, differ but 
little from the imagines as to their digestive canal 
(Z. Dufour, Ann. d. Sc. Nat. III. 1824, Pl. XI. fig. 
7 (Lampyris); Ibid. XIII. 1840, Pl. V. fig. 5 
open ; XIV. 1840, Pl. XI. fig. 9 (Mor- 
ella) ; and Burmeister, Zur Naturg. d. Calandra, 
p. 8, fig. 8.) 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. [X.; Suckow, loc. cit. III. Taf. IIL. 
fig. 87 (Melolontha),; L. Dufour, Ann. d. Sc. 
Nat. XVIII. 1842, Pl. IV. fig. 8, Pl. V. fig. 18 
(Cetonia and Dorcus) ; finally, the excellent work 
of De Haan, Sur les métamorphoses des Coléop- 
téres, Mém. I. les Lamellicornes, in the Nouv. Ann. 
du Mus. IV. 1835, p. 153, Pl. XVI.-XIX. 
35 For this metamorphosis of the intestinal canal, 
see Dutrochet, Jour. de Physique, &., LXXXVI. 
1818, p. 130, or Meckel’s deutsch. Archiv IV. p. 
285, Taf. III. (Bombyx, Myrmeleon, Apis, Polis- 
tes, Tenthredo and Eristalis). This metamor- 
phosis with Sarcoph h rhoidalis has 
been described and figured by L. Dufour, Mém. 
présentés, &c., IX. p. 580, Pl. III. 
86 See Swammerdamm, Bib. der Nat. Taf. 
XXXIV. fig.4; Lyonet, Traité, &c., Pl. XIII. ; 
Ramdohr, loc. cit. Taf. XVIII. fig. 5. Many 
naturalists have carefully observed the metamor- 
phoses of the digestive canal with the Lepidoptera; 
see Herold, Entwi ichte d. Sct 1. 
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, Pl. XIV. fig. 11-13 (Sphinw ligustri). 
This last author has figured the digestive canal ia 
situ in all the three states. 
