264 



THE CEPIIALOPIIORA. 



^229. 



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

 body. With the Ileteropoda, 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 rijiht side at the 

 base of the visceral sac, with Carinaria and Ptero- 

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

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

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

 XXVIII. fig. 10, or Isis, 183-1:, Taf. III. fig. 10) 

 have figured a long bifid penis with Phyllirrhoe 

 mnboinensis ; and so, if with the other Ileteropoda 

 the penis is not retractile, as appears to l)e the case 

 with Carinaria, according to Milne Edwards, 

 this species would be a male, while rhyltirrhoe 

 liucephalus, figui'ed by Piron (Ann. du Museum 

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

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

 a female, although D'Orbigny (Voy. dans I'Amer. 

 m6r., or Isis, 1830, 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 hidividuals he has examined, it 

 may be questioned if the sexes are really separate 

 with this Ileteropod. 



The internal genitaX organsof Atlanta, &ndPhyl- 

 Urrlioe, should be thoroughly studied for the eluci- 

 dation of this point.* 



* [ 5 228, note 9.] See Gegcnbauer (Siebold and 

 Kollitcer''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 [ § 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. v)3) and has since 

 attracted the atteuf.on of Fan Beneden in his em- 

 bryology of Aplysia depilans (Aim. 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 

 (^uoy and Gaimard, loe. cit. 



11 fSuccinum, Murex,Dolium,Harpa,Am.pul- 

 larin, Mitra, Littorina, Stromhus, Cyclostoma. 



1- Janthina, Eburnea, Conus, &c. 



I'! Cassis, Uoliam, Buccinum, Strombiis, Sig- 

 aretus, and Paludina. Vi'ilh Paludina livipara, 

 tlie 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). 



1^ With Dolium, Harpa, Ampullaria, Tritoni- 

 7im, Strombus, &c., 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 orsrau {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. Milller (Zur Kenntniss 

 des Furchungsprocesses ira Schneckeneie, in JVieg- 

 mann\'i Arch. 1848, \}. 1) who ascribes to it a great 

 importance in the primitive developmental changes 

 of the ovmu, and has called it the du-ective vesicle 

 (Vesicula directrix, or Richtungsblaschen). But 

 the special unportance 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 H. Rathki (Wiegmann''s 

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

 Kulliker^s Zeitsch. III. 1S52, p. 373). —Ed. 



1 



