140 
THE VOYAGE OF H.M.S. CHALLENGER. 
the albuminiparous gland ; the male branch is continued in the vas deferens. This last 
is hardly thinner than the duct of the mucous gland, and accompanies it, being 
separated from it by a nerve cord, as far as its entrance into the side wall of the body ; 
it could be traced in company with the vagina as far as the vulva, it then becomes thinner 
and bends forwards and runs in the outer lip of the female genital furrow as far as its 
anterior extremity (PI. VI. fig. 12). In this long portion the vas deferens is firmly em- 
bedded in the substance of the lip, from which it cannot be freed ; in transverse sections 
through the side walls of the body the vas deferens is seen within or near this same lip 
(compressed and perpendicularly oval) (PL VI. fig. 21, c), about ;25 mm. greatest 
diameter, with a very narrow cavity; 1 the course of the vas deferens aldng the body 
wall is (fig. 12) apparently quite straight. I could not follow it as far as the place where 
it appears to enter the frontal shield ; within the last, but nearer the upper side, the 
vas deferens could be separated out, its course here is arched, the length of this portion 
being at least 4 mm. Beneath the right rhinophore, on the outer side of the common 
opening of the dart-gland and praeputium (PI. VI. fig. 12, l), the vas deferens is again 
free (it is of course only visible from the inside of the visceral cavity) ; for the first 8 mm. 
of its length it is somewhat thinner (fig. 12, d ), it afterwards becomes about double 
the thickness, changes in colour from white to brownish-yellow, becomes of a some- 
what softer consistency, and forms a coil, brownish coloured behind (fig. 12, e) and more 
yellowish in front (fig. 12,/); the length of this coil is about 8 mm., and its diameter 
is 6 mm. ; when unrolled, this, th & prostatic portion of the seminal duct (fig. 14, ee), was 
fully 24 cm. in length and A-'o mm. in diameter. Through the axis of the coil runs an 
artery, and a strong connective tissue strand, which anteriorly (fig. 14, i) is prolonged 
into a muscle going towards the penis-sac (fig. 14, h). Behind the prostatic portion 
is continued into the muscular part (fig. 14,/) of the vas deferens, which forms the 
hindermost portion of the coil, and when unrolled has a length of 4 ‘5 cm. Shortly 
before the muscular part of the vas deferens leaves the anterior end of the coil (PL VI. fig. 
14, h), the strong retractor penis muscle is attached to it, which takes its origin behind 
at several points from the body-wall, in the neighbourhood of the anterior end of the 
pericardium ; it is greatly swollen in the middle, and thinner where it is attached to the 
vas deferens (fig. 14, i); from this point the vas deferens takes its course to the penis, 
being slightly thicker (fig. 14, g) ; this portion of the vas deferens is 14 mm. long. 
The p>enis is about 3 ‘5 mm. long, and pear-shaped; it is connected laterally with the 
dart-gland by a transverse cleft (fig. 1 5). The praeputium is rather thick-walled, the 
interior has numerous longitudinal furrows and fine transverse folds ; the upper 
portion of the cavity of the praeputium is nearly filled by the glans, which is about 1 '4 
mm. long, cylindrico-conical, and lined by a strong yellowish cuticle (figs. 16, 17). The 
glans had a round aperture, filled by a small cylindrical evagination, which was perforated 
1 Semper, loc. cit., Landmollusken, Heft v., 1880, Taf. xxii. fig. 20 (Oncliidium glabrum, S.). 
