150 
THE VOYAGE OF H.M.S. CHALLENGER. 
height ; it is very lobate, the number of the larger lobes being about six. The lower 
liver is 1 0 mm. long by 5 mm. broad and 3 mm. in thickness, the number of the larger 
lobes being here three. The hindermost liver is 7 mm. long by 6 '7 5 mm. in breadth and 
about 2 '5 mm. in height; it is, like the others, markedly lobate. The structure is quite 
as usual; the hepatic ducts open in the usual way. 
The pericardium on the inside is, like the visceral cavity, strongly pigmented ; its 
contour is oval, and the length about 8 mm. The heart is as usual; the gastro-hepatic 
artery is very stout, and extends along the under surface of the stomach, giving off a 
special branch to each stomach, and to each of the liver masses. 
The lung cavity is rather narrower than in the preceding species, and about 6 mm. 
long ; its brownish-grey walls are of the usual structure ; the respiratory tube is 3 '5 mm. 
long, with longitudinal folds. The kidney contrasts with the lung cavity by its whitish 
colour. 
The hermaphrodite gland is pale brownish-yellow, and consists of two imperfectly- 
separated halves.. The spermatozoa attain a length of '4 mm., the head alone '013 mm. long. 
The duct is formed of two chief branches, and projects from the hilus of the gland ; these 
branches are each subdivided into two or three twigs ; the common hermaphrodite duct is 
long and spirally wound ; when fully stretched the length is 2 '5 cm., and the diameter '5 -'7 
mm. — The anterior genital mass has the form of a short truncated pyramid, with the base 
directed upwards and anteriorly; its length is 9 '5 mm., the breadth of the base 9 mm., 
and the height 8 mm. ; the hinder end of the mass is formed by the seminal bladder. The 
duct of the mucous gland was followed as far as the vulva (fig. 7, c) ; the spermatheca is as 
usual, its duct slightly longer than the organ itself. The vas deferens , running along the 
vagina, could be traced as far as the outer lip of the genital furrow, considerably thinner 
than the vagina; the course of the vas deferens along the genital furrow as in the previous 
species. It is colourless as far as its entrance into the body cavity (beneath the right 
rhinophore), and was followed in its way through the frontal shield; it then becomes 
black in colour, and a little thicker for about 1 mm. in length, and then increases about 
four times in thickness, and forms a coil, blackish-brown in colour, which, when unrolled, 
measured 5 '5 cm. and '3 mm. in diameter; this coil then passes into another, smaller, 
more longish and whitish in colour, which measured 5 cm. The thickness of this last 
muscular portion of the vas deferens is a little less than that of the prostatic part ; the 
last portion of the muscular part is straight, and measures 1 cm. in length, and is about 
half as thick as the rest of this part. The penis , as already stated by Semper, 1 is of 
unusual length — 5 mm. ; it is cylindrico-conical in shape, and measures behind '75 mm. 
in diameter and 2 mm. in front ; its cavity opens into the male genital cleft, close to the 
dart-sac. The prceputium is thick- walled, with strong transverse furrows on the inside; 
at the base of its cavity is the opening of the vas deferens, the anterior part of this was 
1 Loc. cit., p. 259. 
