264 THE CEPHALOPHORA. $ 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 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,t after which, there appears an usually 
Jong, 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 
‘base of the visceral sac, with Carinaria and Ptero-. 
trachea (Milne Edwards, Ann. d. Sc. Nat. XIII. 
1840, p. 195, XVIII. p. 323, Pl. X. fig. 3). Quoy 
and Gaimard (Voy. de Astrolabe, Mollusq. Pl. 
XXVIII. fig. 10, or Isis, 1884, Taf. ILI. fig. 10) 
have figured a long bifid penis with Phyllirrhoé 
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 Phyllirrhoé 
dbucephalus, figured by Péron (Ann. du Muséum 
XY. fig. 1, or Kosse, De Pteropodum ordine. 
Diss. fig. 1), apparently without a penis, would be 
a female, although D’Orbigny (Voy. dans Amer. 
meér., 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 (Mém. loc. cit. p. 
378, Pl. IX. or Isis, 1832, Taf. VIL.) 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 Atlanta, and Phyl- 
dirrhoé, should be thoroughly studied for the eluci- 
dation of this point.* 
* [§ 228, note 9.] See Gegenbauer (Siebold and 
Kélliker’s Zeitsch. IV. p. 233), who has described 
some follicular penis-glands with Littorina, and 
which serve some purpose in the copulatory act. 
—kEb. 
+ { § 229.] Upon the vitellus of various Gaster- 
opoda, there appears at the time of its segmenta- 
dion, a small round, colorless body, resembling a 
vesicle. ‘his was first mentioned by Pouchet 
(Ann. d. Sc. Nat. 1838, X. p. 63) and has since 
attracted the attention of Van Beneden in 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. 
U1 Buccinum, Murex, Dolium, Harpa, Ampul- 
laria, Mitra, Littorina, Strombus, Cyclostoma. 
12 Janthina, Eburnea, Conus, &c. 
18 Cassis, Dolium, Buccinum, Strombits Bie: 
aretus, and Paludina. With P ud 
the penis is, moreover, so united to the right tentae 
cle, that this last appears to be a detached prolong- 
ation from the inferior surface of its apex (T're- 
viranus, loc. cit. Taf. IV. fig. 18). 
14 With Dolium, Harpa, Ampullaria, Tritoni- 
um, Strombus, &c., this semi-canal extends even 
to the end of the penis (Quoy and Gaimard, loc. 
cit.) ; while with Murez, it- ceases at the base of 
this organ. (Leiblein in Heusinger’s Zeitsch. I. p. 
81, 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- 
silta ventricosa (Held, Isis, 1834, p. 1001), are 
viviparous. 
been brought up by Fred. Miller (Zur Kenntnisw 
des Fur Pp Schneck ,in Wieg- 
mann’s Arch. 1848, p. 1) who ascribes to ita great 
importance in the primitive developmental changes 
of the ovum, and has called it the directive vesicle 
(Vesicula directrix, or Richtungsblaschen). 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 H. Rathké (Wiegmann’s 
Arch. 1848, p. 157) and Gegenbauer (Siebold and 
Kélliker’s Zeitsch. TLL. 1852, p. 373). — Ep. 
ocesses im 
