264 



THE CEPHALOPHORA. 



§ 229. 



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

 as that of the utei'us, until it reaches the extremity of the rectum, when 

 it passes into the ]ienis which always projects from the right side of the 

 body. With the Ileteropoda, the penis is often bifid, but then the semi- 

 nal c.mal does not tiaverse 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 hool^.*^'" With several 

 Pectiiiibranchia, 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 A^ineusta, the 

 Heterobranchia, and the Pulnionata.''' 



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 tloulile and on the right side at the 

 base of tlie visceral sac, with Carinaria and Ptern- 

 trachea {Milne Edwards, Ann. d. So. Nat. XIII. 



1840, p. 1J5, XVIII. p. 323, PI. X. fig. 3). quoy 

 and Gaimard (Voy. de I'Astrolalie, Mollusq. PI. 

 XXVllI. tig. 10, or Isis, 1834, Taf. III. tig. 10) 

 have figured a long bitid penis with PhyUirrhoe 

 amboine.nsis ; and so, if with the otlier Heteropoda 

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

 with Carinaria, according to Milne Edwards, 

 tliis species would be a male, while Phyllirrhoe 

 buceplialus, figured by Piron (Ann. du Museum 

 XV. tig. 1, or Kosse, De Pteropodum ordiiie. 

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

 a female, although U^Orbigny (Voy. dans l'.\ratr. 

 mir., or Isis, 1839, p. 51i3,) regards this genus as 

 hermaphrodite. With Atlanta, there is a simijle, 

 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 Ileteropod. 



The internal genital organs o{ Atlanta, and Phyl- 

 lirrhoe, should be thoroughly studied for the eluci- 

 dation of this pomt.* 



* [ § 223, note 9.] See Gegenbauer (JSiebold and 

 Kolliher's Zeitsch. IV. p. 233), who has described 

 some follicular penis-glands with Littorina, and 

 which serve some purpose in the copulatory act. 

 — Ed. 



t [ § 223.] Upon the vitellus of various Gaster- 

 opoda, there appears at the time of its segmenta- 

 tion, a ^nall 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 atteu'.ion of fan Beneden iu his em- 

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



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



10 For the male genital organs of the Pectini- 

 branchia, see especially the works of Cuvier, and of 

 Quoy and Gaimard, loc. cit. 



11 lincciiium, Murex, Dolium, Harpa, Ampul- 

 laria, Mitra, Littorina, Strombus, Cyclostoma. 



1- Janthina, Eburnea, Conus, &c. 



!•> Cassis, Dolium, Buccinum, Strombus, Sig- 

 aretus, and Paludina. With Paludina nvipara, 

 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- 

 vm, Strombus, kc, this semi-canal extends even 

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

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

 this orgac (Leiblein iu 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- 

 sili.i ventricosa (Held, Isis, 1834, p. 1001), are 

 viviparous. 



been brought ujj by Fred. Mailer (Zur Kenntniss 

 des Furchungsprocesses ira Schneckeneie, in Wieg- 

 m.anri's Arch. 1848, p. 1) who ascribes to it a great 

 importance in the primitive developmental changes 

 of the ovum, and lias called it the directive vesicle 

 (Vesicula directrix, or Kichtungsblaschen). 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 U. Rathki (jyiegmann^s 

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

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



