242 



THE CEPHALOPHORA. 



^211. 



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 ducts/^' It is usually tvv'o 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 (Esophagus, of variable 

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

 crop.^^' The stomach, 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.'''' The cardiac and pyloric ori- 



5 See the description and figures of Troschel 

 <loc. cit. Tivf. IX. X.) of the tongue of our terrestri- 

 al and fresh-water Gasteropoda, and also of Ani- 

 pkipeplea (Ibid. 1839, I. p. 182, Taf. V. fig. 8). 

 For that of the marine Gasterojjoda, see principally 

 Quoy and Gaitnard (loc. cit.), also Poli, Testacea 

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

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

 fig. 2'-»-2", III. fig. 5', S" {Aplysia and Chiton), 

 Rang, Hist. Nat. des Aplysiens, PI. XX. fig. 9-lS 

 (Aplyxia), Delle Chiaje, Menior. &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 Quatrefages, loc. cit. I. PI. IV. V. 

 (^Actaeon and Amphorinn), Alder, Hancock and 

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



XV. PI. I. II. {Fenilia and Aeolis), Allman, Ibid. 



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

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

 Patella, this organ nearly e.xceeds the body in 

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

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

 Trochus pagodas, it is seven times longer than the 

 Isody (Quay and Gaimard, loc cit., and Isis. 1838, 

 p. 69, Taf. IV. fig. 3). With Pleurol/ranchaea, 

 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 

 apines which Eschricht (loc. cit. p. 9) found 

 upon the pliarynx of a Clio, and described as 

 lateral teeth. This apparatus with Pneunio- 

 dermon is quite remarkable — being composed of 

 two tongu-js which are contained in two coecal 

 sheaths (Kan Beneden, Exer. zoot. loc. cit. I'asc. 

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

 tongue consists only of a simi)le transversal row of 

 curved spines. The circle of hooks surrounding 

 the mouth of Sagilta may also be regarded as an 

 abortive tungue (Krohn, loc. cit. p. 7, fig. 3-6), for 

 they are exactly like the lingual spines of Ptero- 

 trachea (Delle Chiaje, JVIem. loc. cit. Tav. LXIX. 

 fig- !)■ 



Lebert has given a very detailed description of 

 the parts of the mouth and the tongue of Patella, 

 Buccinurn, Doris, Ilaliotis, Paludina, and Li- 

 ma.c ; see Mailer's Arch. 1846, p. 435, Taf. XII. 

 -XIV. 



1 The intestine is lined with cilia, with Patella, 

 Buccinurn (Uliarpey, Cyclop, of Anat. I. p. 620), 

 Liymnaeus stagnalis, Paludina vivipara, and 

 Helix cellularis (Purkinje and Valentin, De 



Phaenom. motus vibrat. loc. cit. p. 48), and with the 

 Apneusta (Qu-atrefages, 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 (fVagner's 

 Handwörterbuch d. Physiol. I. p. 492) tlvit ciliated 

 epithelium exists generally in the intestine of tha 

 Gasteropoda. 



A ciliary movement has also been observed in 

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

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

 1846, p. 12). 



'^ The oesophagus is very long with Buccinurn, 

 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 Buccinurn, and Valuta, 

 a, long, 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, 

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

 the crystalline, gelatinous stem, which, according 

 to Cuvier (Ediub. new Philus. Jour. A'll. 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. 



•* Cypraea, Cassis, Murex, Testacella, Limax, 

 Helix, &c. 



5 Lymnaeus, Planorbis, Thetis. 



ß There are three horny lamellae in the stomach 

 of Bullaea (Cuvier, loc. cit. fig. 11), and of cer- 

 tain species o{ Pleurobranchus (Meckel, Ueitr. &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 plates 

 (Quatrefages, loc. cit. I. p. 153, PI. IV. fig. 5, V. 

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

 KoUiker. With Sryllaea (Cuvier, loc. cit. fig. 6, 

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

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

 lae with sharp edges. With üentalium also, the 

 entrance of the stomach has a very complicated 

 dental apparatus (Desliayes, loc. cit. p. 333, PI. 

 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 



