The Norw. North-Atlantic Exped. 
13 
are found (Pl. II fig. 5 b); in which, with the aid of a powerful 
magnifying glass, small, scattered, suckers are seen, that appear to 
stand two and two together. The covering mentioned is pretty 
firmly attached to the ribs and does not clothe the whole of the 
body, as the uppermost part is exposed for a length of 4—5 m. m. 
from the oral disc (Pl. II, fig. 5 c) but, on the other hand, it is 
found clothing the whole of the posterior part, with exception of 
the extremity, which is furnished with a round aperture (anus) that 
dilates and contracts itself, and through which the excrementa are 
ejected in the shape of plugs of course sand and mucous (Pl. II 
fig. 5 d). 
In the superior (anterior) naked part, which dilates itself, some- 
what, towards the oral disc, the 12 ribs appear still more distinctly, 
and between them the suckers are more distinctly observed and 
are a little larger than on the rest of the body. 
The oral disc is a good deal broader than the anterior margin 
of the body; it is rather plane, but folded, and is a little depressed 
towards the slightly oblong oral aperture situated in the middle 
(Pl. II fig. 1, 5, 7). The folds, which issue from the oral aperture 
radially, towards the periphery, are narrowest at their origin, but 
gradually become broader towards the margin of the oral disc, 
which is furnished with 12 tentacles standing in a series (Pl. II 
fig. 1, 7). These are rather short, thick at the base, and retractile. 
The tentacles, as well as the oral disc and the entire anterior ex- 
posed part of the body, are capable of being withdrawn into the 
vaginal mucous covering, which then appears to form a tube that 
closes itself at the top. This tube is, otherwise, very thin and trans- 
parent, and is easily detached from the body, but, yet, is so well se- 
cured to the longitudinal ribs that the animal cannot quite throw it off. 
Detached portions are quickly replaced by exudation of a viscid 
substance from the naked exterior surface of the body. 
The colour. The tube, or the mucous covering, is a beauti- 
ful chestnut brown, having a violet play of colour. The integument 
of the body is pale rosy-red. The oral disc and the tentacles are 
an intense crimson-red, but the disc is a little paler in colour than 
the tentacles. 
Upon dissecting the animal longitudinally it becomes immedi- 
ately evident, that we have, here, an internal arrangement like 
that described in connection with Fenja mirabilis. Here, there is 
an absence of gastrovascular cavity, as the gullet-tube passes im- 
