264 



THE CEPIIALOPHORA. 



^229. 



The course of the seminal duct, and that of the oviduct also, is tlie same 

 as that of the uterus, until it reaches the extremity of the rectum, when 

 it passes into the penis which always projects from the right side of the 

 Tjody. With the Heteropoda, the penis is often bifid, but then the semi- 

 nal canal does not traverse except one of its divisions.*^' 



With the Gasteropoda, the penis is either very long,^^"' tongue-shaped and 

 often flexuous,'"* or short and lanceolate. '^^* It projects under and usually 

 behind the right tentacle, and extends upon the side of the body — rarely 

 being in a wholly retracted state, but is capable of being easily folded under 

 the border of the mantle. 



With some genera, its extremity has a small hook.<^"' With several 

 Pectinibranchia, the seminal canal terminates behind the anus, and then 

 takes the form of a furrow, which communicates with the base of the penis, 

 extending even to its extremity, either as an external, or an internal semi- 

 canal.*"' 



§ 229. 



The development of the Cephalophora has, as yet, scarcely been observed 

 except with the Gasteropoda, and in particular with the Apneusta, the 

 Heterobranchia, and the Pulmonata.*^' 



All observations concur as to the fact that the vitellus undergoes a reg- 

 ular and complete segmentation,! after which, there appears an usually 

 long, round embryo, one of the poles of which is indented and covered with 



9 The penis is double and on the right side at the 

 baseof tlie visceral sac, with Carinaria and Pte.ro- 

 trachea (Milne Edwards, Ann. d. Sc. Nat. XIII. 

 1S40, p. 195, XVIII. p. 323, PI. X. fig. 3). quoy 

 and Gaimard (Voy. de 1' Astrolabe, MoUusq. PI. 

 X.XVIII. fig. 10, or Isis, 1S34, Taf. III. fig. 10) 

 have figured a long bifid penis with Phyllirrhoe 

 amboinensis ; and so, if with the other Heteropoda 

 the penis is not retractile, as appears to be the case 

 with Carinaria, according to Milne Edwards, 

 this species would be a male, while Phyllirrhoe 

 bucephalus, figured by Piron (Ann. du Museum 

 XV. fig. 1, or Kosse, De Pteropodura ordine. 

 Diss. fig. 1), apparently without a penis, would be 

 a female, although WOrbigny (Voy. dans I'Am^r. 

 m6r., or Isis, 1839, p. 519,) regards this genus as 

 hermaphrodite. With Atlanta, there is a simple, 

 pointed penis on the right side of the neck directly 

 near the arms ; but as Rang (Mem. loc. cit. p. 

 378, PI. IX. or Isis, 1832, Taf. VII.) has found this 

 penis with all the individuals he has examined, it 

 may be questioned if the sexes are really separate 

 with this Heteropod. 



The internal genital organs of J</ara<a, and PAyZ- 

 lirrhoe, should be thoroughly studied for the eluci- 

 dation of this pomt.* 



* [ §. 228, note 9.] See Gegenbauer (Siebold and 

 Källiker^s Zeitsch. IV. p. 233), who has described 

 eome follicular penis-glands with Littorina, and 

 which serve some purpose in the copulatory act. 

 — Eu. 



t [ § 229.] Upon the vitellus of various Gaster- 

 opoda, there appears at the time of its segmenta- 

 tion, a small round, colorless body, resembling a 

 vesicle. This was first mentioned by Pouchet 

 (Ann. d. Sc. Nat. 1838, X. p. 63) and has since 

 attracted the attention of Fail ßeneden in his em- 

 bryology of Aplysia depilans (Ann. d. Sc. Nat. 

 1841, XV. p. 126). Quite recently, the suliject has 



10 For the male genital organs of the Pectini- 

 branchia, see especially the works of Cuvier, and of 

 Quoy and Gaimard, loo. cit. 



11 Buccinum, Murex, Dolium, Harpa, Ampul- 

 laria, Mitra, Littorina, Strombus, Cyclostoma, 



12 Janthina, Eburnea, Conus, &c. 



13 Cassis, Dolium, Buccinum, Strombus, Sig- 

 aretus, and Paludina. With Paludina vivipara, 

 the penis is, moreover, so united to the right tenta- 

 cle, that this last appears to be a detached prolong- 

 ation from the inferior surface of its apex (Tre- 

 viranus, loc. cit. Taf. IV. fig. 18). 



14 With Dolium, Harpa, Ampullaria, Tritoni- 

 um, Stro?nbus, &c., this semi-canal extends even 

 to tlie end of the penis (Quoy and Gaimard, loc. 

 cit.) ; while with Murex, it ceases at the base of 

 this organ (Leiblein in Heusinger^s Zeitsch. I. p. 

 31, Taf. I.). 



1 With the Cephalophora, the embryonic devel- 

 opment does not generally begin until after the eggs 

 have been deposited. A few only of the Gasteropo- 

 da, and among them Paludina vivipara, and Clau- 

 silia ventricosa (Held, Isis, 1834, p. 1001), are 

 viviparous. 



been brought up by Fred. Müller (Zur Kenntnis« 

 des Furchungsprocesses im Schneckeueie, in Wie^- 

 mann^s Arch. 1848, p. 1) who ascribes to it a great 

 importance in the primitive developmental changes 

 of the ovum, and has called it the directive vesicle 

 {Vesicula directrix, or Richtungsbläschen). But 

 the special importance of this body seems not yet 

 well made out, and it may be questioned if it is not 

 rather a secondary formation, than a primitive, di- 

 rective organ. See i/. Rathki (IViegmann's 

 Arch. 1848, p. 157) and Gegenbauer (Siebold and 

 Kolliker's Zeitsch. 111. 1852, p. 373). —Ed. 



