242 $ 214. 
THE CEPHALOPHORA. 
points of these spines turn backwards, and thus the retractile tongue can 
serve as an organ of ingestion, and as such is used with much address. 
§ 214. 
The intestinal canal has often longitudinal folds and a ciliated epithe- 
lium extending from the ossophagus to the rectum, and even into the 
hepatic ducts.” It is usually two or three times the length of the body, 
and has therefore several convolutions, which, with the species which have 
a shell, are contained in its spiral cavity. 
It commences at the base of the pharynx by an Csophaeus, of variable 
length, which is sometimes dilated at its posterior extremity into a kind of 
crop.? The stqmach, which, from constrictions, is often divided into 
several portions, consists sometimes of a simple dilatation with thin 
walls,“ and at other times of’ a nicely-defined cavity whose walls are thick 
and fleshy, and provided, sometimes, with thick epithelium, and even, in 
certain cases, with plates and horny teeth. 
5 See the description and figures of T'roschel 
(oe. cit. Taf. IX, X.) of the tongue of our terrestri- 
al and fresh-water Gasteropoda, and also of Am- 
phipeplea (Ibid. 1839, I. p. 182, Taf. V. fig. 8). 
For that of the marine Gasteropoda, see principally 
Quoy and Gaimard (loc. cit.), also Poli, Testacea 
Siciliae, &c., I. p. 5, Tab. IIL. fig. 9 (Chiton), Sa- 
vigny, Descrip. de ?Egypte, Hist. Nat. II. Pl. IL. 
fig. 2-213, IIT. fig. 57, 53 (Aplysia and Chiton), 
Rang, Hist. Nat. des Aplysiens, Pl. XX. fig. 9-13 
(Aplysia), Delle Chiaje, Memor. &c. Tav. XV. 
fig. 7-10 (Carinaria), and Eschricht, loc. cit. p. 
10, Tab. ILI. fig. 20-23 (Clio). 
The tongue is very long with most of the Ap- 
neusta ; see Quatrefages, loc. cit. I. Pl. IV. V. 
(Actaeon and Amphorina), Alder, Hancock and 
Embleton, Ann. of Nat. Hist. XIII. Pl. II. fig. 5-6, 
XV. PL I. Il. (Venilia and Aeolis), Aliman, Ibid. 
XVI. Pl. VI. VII. fig. 5 (Actaeon), and Nord- 
mann, loc. cit. Tab. I. fig. 7-10 (Tergipes). With 
Patelia, this organ nearly exceeds the body in 
length, and bends loop-like, near its posterior ex- 
tremity (Cuvier, Mém. loc. cit. Pl. IL). With 
Trochus pagodus, it is seven times longer than the 
body (Quoy and Gaimard, loc cit., and Isis. 1836, 
p. 69, Taf. IV. fig. 3). With Pleurobranchaea, 
there are spines, not only on the tongue, but 
on a considerable portion of the lateral walls of 
the oral cavity. To the same category belong the 
spines which Eschricht (loc. cit. p. 9) found 
upon the pharynx of a Clio, and described as 
lateral teeth. This apparatus with Pneumo- 
dermon is quite remarkable — being composed of 
two tongues which are contained in two coecal 
sheaths (Van Beneden, Exer. zoot. loc. cit. Fasc. 
I. p. 47, Pl. IL. fig. 2). With Pterotrachea, the 
‘ tongue consists only of a simple transversal row of 
eurved spines. The circle of hooks surrounding 
the mouth of Sagitta may also be regarded as an 
abortive tongue (Krohn, loc. cit. p. 7, fig. 3-6), for 
they are exactly like the lingual spines of Ptero- 
eee (Welle Chiaje, Mem. loc. cit. Tay. LXIX. 
g. 1). 
Lebert has given a very detailed description of 
the parts of the mouth and the tongue of - Patedla, 
Buccinum, Doris, Haliotis, Paludina, and Li- 
mae see Muller’s Arch. 1846, p. 485, Taf. XII. 
1 The intestine is lined with cilia, with Patedla, 
Buccinum (Sharpey, Cyclop. of Anat. I. p. 620), 
Lymnaeus stagnalis, Paludina vivipara, and 
Helix cellularis (Purkinje aud Valentin, De 
The cardiac and pyloric ori- 
Phaenom. motus vibrat. loc. cit. p. 48), and with the 
Apneusta (Quatrefages, Ann. d. Sc. Nat. I. p. 166). 
I have also seen the ciliary motions, with Lym- 
naeus, Planorbis, and Clausilia; but not with 
Limaz, Arion, and Helix. Valentin may, 
therefore, be mistaken in affirming (Wagner's 
- Handwiorterbuch d. Physiol. I. p. 492) that ciliated 
epithelium exists generally in the intestine of the 
Gasteropoda. 
A ciliary movement has also been observed in 
the intestine of Sagitta by Krohn (loc. cit. p. 8), 
and by Wilms (Observ. de Sagitta, Diss. Berolini, 
1846, p. 12). 
2 The cesophagus is very long with Buccinum, 
Paludina, Lymnaeus, and Planorbis ; but very 
short with Thetis, Haliotis, Testacella, Helix, 
and Lima. It has a kind of crop close upon the 
h with Cymbulia, Onchidium, Ly 8, 
and Planorbis, while with Buccinum, and Voluta, 
along, crop-like’caecum arises from the upper por- 
tion of the stomach near the cesophagus. 
3 Aplysia, Dolabella, Notarchus, Ancylus, 
Pleurobranchus, and Onchidium; see Cuvier, 
Mém. loc. cit. Iam unable to say anything upon 
the crystalline, gelatinous stem, which, according 
to Cuvier (Edinb. new Philos. Jour. VIL. 1829, p. 
225, and Isis, 1832, p. 815) is found In all the 
species of Strombus and some of T'rochus and 
Murezs;, and is contained in an internally projecting 
appendix of the stomach. 
4 Cypraea, Cassis, Murex, Testacella, Liman, 
Heliz, &c. 
5 Lymnaeus, Planorbis, Thetis. J 
6 There are three horny lamellae in the stomach 
of Bullaea (Cuvier, loc. cit. fig. 11), and of cer- 
tain species of Pleurobranchus (Meckel, Beitr. &c. 
I. Hft. 1, p.31, Tab. V. fig. 36, 37) ; four in that of 
Cymbulia, Tiedemannia, Hyalen, and Limacina 
(Van Beneden, Exerc. zoot. loc. cit. Fase IT.) 
That of Pe/ta has four denticulated horny plates 
(Quatrefages, loc. cit. I. p. 153, Pl. IV. fig. 5, V. 
fig. 7), as is also true of Lissosoma, according to 
Kolliker. With Scyllaea (Cuvier, loc. cit. fig. 6, 
d.), and with T'ritonia (Mecked, Syst. d. vergleich. 
Apat. IV. p. 188), there is a complete row of lamel- 
Jae with sharp edges. With Dentalium also, the 
entrance of the stomach has a very complicated 
dental apparatus (Deshayes, loc. cit. p. 333, Pl. 
XV. fig. 13, or'Isis. 1832, p. 463, Taf. VI. fig. 17). 
But Aplysia, of all the Cephalophora, is best 
provided for in this respect, for here the second 
muscular stomach is lined with a triple row of 
