§279. 



THE CRUSTACEA. 331 



nioiidae, 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 oesophagus, 

 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 stiiF cilia, or pre^^ents 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 

 oesophagus, 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 fi-om 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.'^"* 



S For the arcuate intestine of Daphnia, Lyn- there are in the cardiac region of the stomach two 



ceMS, and Polyphemus, see the figures given by lateral horny tridentate folds (Ro!<s,9eide Fauzeme, 



Jurine, Hist. d. Monocl. ; Straus, loc. cit. PI. loc. cit. p. 251, PI. VIII. fig. 13, 14). 

 XXIX. (Daphnia) ; Brongniart, loc. cit. PI. 9 With Limulus, the cesophagus extends in 



XHI. (Limtiadia) ; Straus, Mus. Senckenb. loc. front and opens into a very muscular backwardly- 



cit. p. il2, Taf. VII. fig. 12, and Jo!y, loc. cit. PI. cui-ved stomach the epithelium of which has fifteen 



VII. fig. 5 ([saura). With Cypris, there is a kind longitudinal rows of horny teeth {Van der Hoeven, 

 of stomach on the curved digestive canal (Straus, loc. cit. p. 17, PI. II. fig. 3. B.). With Squilla, 

 loc. cit. p. oO, PI. I. fig. 10). the stomach is pyramidal, and has, at its pyloric 



fi For the intestine and stomach of the Cirripe- region, horny plates and very regular rows of hairs 



dia, see the writings oi Cuvier, Burmeister, and (Duvernoy, in Cuvier's Legons d'Anat. Comp. 



Martin St. Ans:e ; also Roussel de Vauzime, loc. V. p. 231). With Mysis, also, the epithelium of 



cit. PI. VIII. tig. 12, 18 (Cyamus) ; Brandt, the pyriform stomach is supported by several soUd 



Mediz.Zool. II. Tab. XV. fig. 39 (One'scas); />ere- lamellae composed of chitine and covered with 



boullet, loc. cit. p. 126, PI. V. fig. 25 {Lygidium), bristles mixed with hairs (Frey, loc. cit. p. 16). 



and Rathlce, loc. cit. Taf. IV. fig. 19 (Idothea). W The stomach of the Crawfish is the one best 



I See Ramdohr, Abhandl. ub. d. Verdauungsw. known ; see the descriptions and figures given by 



d. Insek. p. 1-iS, Taf. XV. fig. 1; Treviranus, Roesel, Sackow, Brandt, loc. ciL, and Milne Ed- 



Verm. Schrift. II. p. 23,43, Taf. V. fig., 4, Taf. wards. Hist. d. Crust. I. p. 67, PI. IV. The inti- 



VIII. fig. 6 (Lithobius and Julus) ; L. Dufour, mate structure of this stomach and its internal 

 loc. cit. p. 84, 95, PI. V. fig. 1, 4 (Lithobius and appendages have been carefully studied by Falen- 

 Scutigera) ; Kutorga, loc. cit. p. 5, Tab. I. fig. 2 tin (Repertorium, I. p. 115, Taf. I. fig. 15-21) and 

 (Scolopendra) ; and Brandt, in Muller^s Arch, by Oesterlen (Miiller^s Arch. 1840, p. 387, Taf. 

 loc. cit. Taf. XII. fig. 2 (Glomeris).* XII.). 



« The stomach of Oniscus contains a cartilagi- The teeth and bristles here observed, are found 



nous support of a peculiar form (Brandt, Mediz. also with the three divisions of the Decapoda. I 



Zool. II. p. 74, Taf. XV. fig. 41, 42). That of the have seen them with Homarus, Patinurus, Gala- 



stomach of Idothea entomon is composed of seve- thea, Pagurus, Cancer, Maia, Lupea, &c. 



ral solid pieces (Rathki, loc. cit. p. 119, Taf. IV. With Crangon, and Palaemon, I found the dental 



fig. 20, 21). With Lygidium, the epithelium is lamellae wanting but the epithelium was hairy, 



supported by several horny pieces, and provided With Caridina, according to Joly (loc. cit. p. 73, 



with numerous stiff bristles (Lereboullet, loc. cit. PI. III. fig. 27), hairs of this kind are inserted on 



p. 127, PI. V. fig. 26-30). Finally, with Cyamus, the band-like condensations of the stomach. 



* [ § 279, note 7.] For the aUmentary canal of Fauna within living Animals, in Smithsonian Con- 

 Julus in all its details, see Leidy, A Flora and tributions to Knowledge, V. 1853. — Ed. 



