148 
THE VOYAGE OF H.M.S. CHALLENGER. 
entire length of the gland, the lateral walls especially projecting along the middle of the 
length ; the walls of the cavity were somewhat spongy ; the gland follicles appeared to he 
quite like those of other species. The walls of the efferent duct had fine longitudinal 
folds. This gland is perhaps in some way connected with the genital function, perhaps 
oviposition. 
For comparison I further examined the following species. 
Onchidium verruculatum, Cuvier (PL VII. figs. 7-12 ; PI. VIII. fig. 14). 
Onchidium verruculatum , Cuvier, Regne Animal, 2 me fid., t. iii., 1830, p. 46 (footnote 1 ). 
„ Semper, loo, cit., pp. 255-257, Taf. xxi. fig, 1 ; Taf. xxii., figs. 3, 4. 
Habitat. — Indian Ocean. 
I investigated a single specimen of this species, which was taken during the “ Galathea” 
Expedition, by Prof. Reinhardt, in February 1846, on the north shore of Sambelong 
(Great Nicobar), in the Ganges Harbour. The specimen had been determined by 
Semper. 
The specimen had been well preserved in alcohol, and was only slightly contracted ; it 
was 3 '3 cm. in length, 2'3 cm. in breadth, and IT cm. in height; the breadth of the 
mantle edge 4 - 5 mm., of the' foot 18 mm., of the head 15 mm.; the length of the 
rhinophoria 3 mm.; the free anterior edge of the foot projects 2 mm.; the length of the 
tail is 2'5 mm., the width of the pneumostome 2 mm. 
The pseudo-peritoneum is black in colour, its diaphragm greyish. The position of the 
organs of the body was quite as in the previous species. 
The central nervous system 2 as above ; the pleural ganglia were, however, relatively 
larger than in the specimens previously investigated. The dorsal eyes (PI. VIII. fig. 14) 
which have been accurately described by Semper, 3 were present in small numbers ; I counted 
about twenty groups of eyes, each containing from three to four ; their structure was as 
described by Semper. The rhinophoria and the eyes situated upon them as usual ; the 
cavity of the former was entirely free from pigment. I did not succeed in discovering 
the otocysts. 
1 In the second Edition of the Eegne Animal, Cuvier named the Onchidium, figured in the Description de 
I’Egypte, Onchidium verruculatum. This name was first adopted by Keferstein (Einige Bemerk. fiber d. Geschlechtsorg. 
von Peronia verruculata, Cuvier. Zeitschr. f. wiss. Zool., Bd. xv., 1864, p. 91) for individuals from Java and Japan. But 
this identification appeared probable first through the comparative researches of Semper (Joe. cil., 1880, p. 256), who had 
investigated a number of individuals from the Bed Sea to beyond the middle of the Pacific of this widely distributed 
species. 
2 The nervous system is treated of by v. Jhering ( loc . cit., p. 230, Taf. iv. fig. 16). 
:t Loc. cit., Landmollusken. Erganzungsheft, 1877, p. 4, Taf. A. fig. 5 ; Taf. B. figs. 1, 2 ; — Heft v., 1880, 
pp. 255-256. 
