$ 279. THE CRUSTACEA. 381 
nioidae, and Apodidae, on the contrary, its anterior extremity mounts 
towards the dorsal surface of the head, and then curves backwards to the 
mouth, 
With the other Crustacea, there is, more or less distant from the cesophagus, 
a stomach, formed by a pyloric constriction of the intestine. This stomach 
is small with the Cirripedia, Laemodipoda, Isopoda, and Amphipoda ; © 
but is pretty long with the Myriapoda. In many of the Isopoda and 
Laemodipoda, the stomachic epithelium has stiff cilia, or presents a carti- 
laginous, or horny aspect, thus constituting a stomachic support and dental 
apparatus,® which is also observed in the somewhat larger stomach of the 
Poecilopoda and Stomapoda.© But this structure of the stomach is most 
prominent with the Decapoda. Remarkable for its size and form, it con- 
sists of two portions; one, anterior, vesiculiform, communicating with the 
esophagus, the other pyloric, pyramidal, and with the apex pointing back- 
wards. The internal tunic of the stomach is composed of chitine and 
covered with stiff bristles, or sometimes with groups of very singular hairs 
of a forficulate form. Moreover, its callous and cartilaginous portions 
form, in the pyloric region, a remarkable support, on which are three solid 
movable pieces. One of these pieces is a single tooth placed in the middle 
of the posterior wall of the stomach; while the other two, longer and 
somewhat crenulated, are situated on the sides opposite each other. Seve- 
ral muscles, arising from the internal surface of the cephalothorax, are in- 
serted on this stomach, and it is very probable that, by these, the animal 
can voluntarily bring the three pieces together, making them serve as inter- 
nal masticatory organs. 
5 For the arcuate intestine of Daphnia, Lyn- 
.ceus, and Polyphemus, see the figures given by 
Jurine, Hist. d. Monocl.; Straus, loc. cit: Pl. 
XXIX. (Daphnia) ; Brongniart, loc. cit. Pl. 
XILL. (Limnadia) ; Straus, Mus. Senckenb. loc. 
cit. p. 112, Taf. VII. fig. 12, and Jo/y, loc. cit. Pl. 
VIL. fig. 5 (Isaura). - With Cypris, there is a kind 
of stomach on the curved digestive canal (Straus, 
loc. cit. p. 60, Pl. I. fig. 10). 
6 For the intestine and stomach of the Cirripe- 
dia, see the writings of Cuvier, Burmeister, and 
Martin St. Ange ; also Roussel de Vauzeme, loc. 
cit. Pl. VILL. fig. 12, 18 (Cyamus); Brandt, 
Mediz. Zool. IL. Tab. XV. fig. 39 (Oniseus) ; Lere- 
boullet, loc. cit. p. 126, Pl. V. fig. 25 (Lygidium), 
and Rathke, loc. cit. Taf. IV. fig. 19 (ddothea). 
7 See Ramdohr, Abhandl. ib. d. Verdauungsw. 
d. Insek. p. 148, Taf. XV. fig. 15 Treviranus, 
Verm. Schrift. II. p. 23,438, Taf. V. fig. 4, Taf. 
VILL. fig. 6 (Lithobius and Julus); L. Dufour, 
loo. cit. p. 84, 95, Pl. V. fig. 1, 4 (Lithobius and 
Scutigera); Kutorga, loc. cit. p. 5, Tab. I. fig. 2 
(Scolopendra) ; and Brandt, in Muller’s Arch. 
loc. cit. Taf. XII. fig. 2 (Glomeris).* fn 
8 The stomach of Oniscus contains a cartilagi- 
nous support of a peculiar form (Brandt, Mediz. 
Zool. Il. p. 74, Taf. XV. fig. 41, 42). That of the 
stomach of Idothea entomon is composed of seve- 
ral solid pieces (Rathké, loc. cit. p. 119, Taf. Ty. 
there are in the cardiac region of the stomach two 
lateral horny tridentate folds (Roussel de Vauzéme, 
loc. cit. p. 251, Pl. VIIL. fig. 13, 14). 
9 With Limulus, the cesophagus extends in 
front and opens into a very muscular backwardly- 
curved stomach the epithelium of which has fifteen 
longitudinal rows of horny teeth (Van der Hoeven, 
loc. cit. p. 17, Pl. IL. fig. 3. B.). With Squidia, 
the stomach is pyramidal, and has, at its pyloric 
region, horny plates and very regular rows of hairs 
Duvernoy, in Cuvier’s Legons d’Anat. Comp. 
. Pp. 231). With Mysis, also, the epithelium of 
the pyriform stomach is supported by several solid 
lamellae composed of chitine and covered with 
bristles mixed with hairs (Frey, loc. cit. p. 16). 
10 The stomach of the Crawfish is the one best 
known ; see the descriptions and figures given by 
Roesel, Suckow, Brandt, loc. cit., and Milne Ed- 
wards, Hist. d. Crust. I. p. 67, Pl. LV. The inti- 
mate structure of this stomach and its internal 
appendages have been carefully studied by Valen- 
tin (Repertorium, I. p. 115, Taf. I. fig. 15-21) and 
by Oesterlen (Muller’s Arch. 1840, p. 387, Taf. 
IL.). 
The teeth and bristles here observed, are found 
also with the three divisions of the Decapoda. I 
have seen them with Homarus, Palinurus, Gala- 
thea, Pagurus, Cancer, Maia, Lupea, &c. 
With Crangon, and Palaemon, I found the dental 
fig. 20, 21). With Lygidium, the ep m is 
supported by several horny pieces, and provided 
with numerous stiff bristles (Lerebou/let, loc. cit. 
p. 127, Pl. V. fig. 26-80). Finally, with Cyamus, 
*[ § 279, note 7.] | For the alimentary canal of 
Julus in all its details, see Leidy, A Flora and 
llae wanting but the epithelium was hairy. 
With Caridina, according to Joly (loc. cit. p. 73, 
Pl. III. fiz. 27), hairs of this kind are inserted on 
the band-like cond ions of the st h 
Fauna within living Animals, in Smithsonian Cone 
tributions to Knowledge, Y. 1853. — Ep. 
