242 



THE CEPHALOPHORA. 



^214, 



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 oesophagus to the rectum, and even into the 

 hepatic duets.*" 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 CEsophagus, of variable 

 length, which is sometimes dilated at its posterior extremity into a kind of 

 *-' The stomach, which, from constrictions, <''' is often divided into 

 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. *'" The cardiac and pyloric ori- 



crop 

 sevcra 



S See the description and figures of Troschel 

 (loc. 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 

 Quay and Gaimard (loc. cit.), also Poli, Testacea 

 Siciliae, &c., I. p. 5, Tab. III. fig. 9 (^Chiton), Sa- 

 vigny, Descvip. de I'Egypte, Hist. Nat. II. PI. II. 

 fig. 2-1-213, III. fig. 5', S-* {Aplysia and Chiton), 

 Rang, Hist. Nat. des Aplysieus, PI. XX. fig. 9-13 

 (Aplysia), Delle Chiaje, Meraor. &c. Tav. XV. 

 fig. 7-10 {Carinaria), and Eschricht, loc. cit. p. 

 10, Tab. III. fig. 20-23 {Clio). 



The tongue is-very long with most of the Ap- 

 neusta ; see Qiiatrefages, loc. cit. I. PI. IV. V. 

 (Actaeon and Amphnrina), Alder, Hancock and 

 Emhleton, Ann. of Nat. Hist. .XIII. PI. II. fig. 5-6, 



XV. PI. I. II. {renilia and Aeolis), Aliman, Ibid. 



XVI. PI. VI. VII. fig. 5 (Actaeon), and Nord- 

 mann. Inc. cit. Tab. I. fig. 7-10 {Tergipes). With 

 Patella, tliis organ nearly exceeds the body in 

 length, and bends loop-like, near its posterior ex- 

 tremity (Cuvier, Mem. loc. cit. PI. II.). With 

 Troc/ius pagodus, it is seven times longer than the 

 body {Qiioy 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 Esckricht (loc. cit. p. 9) found 

 upon the pharynx of a Clio, and described as 

 lateral teeth. This appai-atus with Pneumo- 

 dermon is quite remarkable — being composed of 

 two tongues which are contained in two coecal 

 sheaths (Frt« Beneden, Exer. zoot. loc. cit. Fasc. 

 I. p. 47, PI. II. fig. 2). With Plerotrachea, the 

 tongue consists only of a simple transversal row of 

 curved spines. Tlie circle of hooks surrounding 

 the mouth of Sagitta may also be regarded as an 

 abortive tongue {Krohn, loc. cit. ij. 7, fig. 3-6), for 

 they are exactly like the lingual spines of Plero- 

 trachea {Delle Chiaje, Mem. loc. cit. Tav. LXIX. 

 fig- 1). 



Lebert has given a very detailed description of 

 the parts of the mouth and the tongue of Patella, 

 Buccinum, Doris, Haliotis, Paludina, and Li- 

 max ; see Muller's Aixh. 1846, p. 4^35, Taf. XII. 

 -XIV. 



1 The Intestine is lined with cilia, with Patella, 

 Buccinum {Sharpey, Cyclop, of Anat. I. p. 620), 

 Lymnaeus stagnalis, Paludina vivipara, and 

 Helix cellularis {Purkinje and yalentin, De 



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 

 Limax, Arion, and Helix. Valentin may. 

 therefore, be mistaken in affirming {IVagner's 

 Handwiirterbuch d. Physiol. I. p. 492) that ciliated 

 epithelium exists generally in the intestine of the 

 Gasteropoda. 



A ciliary movement has also been observed iu 

 the intestine of Sagitta by Krohn (loc. cit. p. 8), 

 and by fVilms (Observ. de Sagitta, Diss. Berolini, 

 1846, p. 12). 



- The (Esophagus is very long with Buccinum, 

 Paludina, Lymnaeus, and Planorbis ; but very 

 short with Thetis, Haliotis, Testacella, Helix, 

 and Limax. It has a kind of crop close upon the 

 stomach with Cymbulia, Onchidium, Lymnaeus, 

 and Planorbis, while with Buccinum, and P'oluta, 

 a long, crop-like caecum arises from the ujjper por- 

 tion of the stomach near the oesophagus. 



3 Aplysia, Dolabella, Notarchus, Ancylus, 

 Pleurobranchus, and Onchidium ; see Cuvier, 

 Mem. loc. cit. I am unable to say anything upon 

 the crystalline, gelatinous stem, which, according 

 to Cuvier (Edinb. new Philos. Jour. VII. 1829, p. 

 225, and Isis. 1832, p. 815) is found in all the 

 species of Strombus and some of Trochus and 

 Murex, and is contained in an internally projecting 

 appendix of the stomach. 



i Cypraea, Cassis, Murex, Testacella, Limax, 

 Helix, &c. 



•i Lymnaeus, Planorbis, Thetis. 



C 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, Hyalea, and Limacina 

 {Van Beneden, Exerc. zoot. loc. cit. Fasc II.). 



That of Pelta has four denticulated horny jilatcs 

 {Quatrefages, loc. cit. I. p. 1.53, PI. IV. fig. 5, V. 

 fig. 7), as is also true of Lissosoma, according to 

 holliker. AVith Scyllaea {Cuvier, loc. cit. fig. 6, 

 d.), and with Tritonia {Meckel, Syst. d. vergleich. 

 Anat. IV. ]). 188), there is a complete row of lamel- 

 lae with sharp edges. With Dentalium also, the 

 entrance of the stomach has a very complicated 

 dentiil ajiparatus {Deshayes, loc. cit. p. 333, PI. 

 XV. fig. 13, or Isis. 1832, p. 463, Taf. VI. fig. 17). 

 lUit Aplysia, of all the Cephalophora, is best 

 Ijrovided for in this respect, for here the second 

 muscular stomach is fined with a triple row of 



