38 
THE VOYAGE OF H.M.S. CHALLENGES. 
from Station 203 (Martinique), where Actinometra discoidea also occurred ; but as the 
parasite was unattached, it may have belonged to one of the other Comodulce occurring 
at this Station ( Actinometra meridionalis ?). 
16. Myzostoma brevipes, n. sp. (PI. III. figs. 19, 20). 
In size and stoutness of build this species is intermediate between Myzostoma glabrum 
and Myzostoma cirriferum ; it has, like the latter, a transparent marginal border, from 
which arise twenty short cirri, ‘16 mm. long. The back is a bright gamboge-colour, 
and covered by deep folds ; the larger of these were no doubt caused by the alcohol, but 
the finer peripheral folds correspond to the branches of the intestine. The flat ventral 
surface is a dull greyish-brown ; the parapodia take their origin from small cavities on the 
ventral surface (see ideal section, fig. 20). They are, however, feeble and short (T8 mm. 
long), and reach but a little way beyond the margin of the cavities. Beyond the latter 
are traces of flat suckers. The diameter of the disc in the largest specimen is 2*3 mm. 
Host. — Antedon pourtalesii, P. H. C., from Station 241 (off Carriacou) of the 
“ Blake ” Expedition. 
17. Myzostoma carpenteri, Graff (PL II. figs. 10-15). 
Myzostoma carpenteri, Graff, Proc. Eoy. Soc. Edin., vol. xii. p. 380, 1884. 
The adult individuals of this species, which I name in honour of my friend Dr P. 
Herbert Carpenter, are of a light yellow colour with fine wrinkles. The body is robust, 
and is everywhere of considerable thickness, as shown by the ideal section (fig. 14). The 
anterior margin is somewhat indented, the hind margin obtusely pointed ; the diameter 
is somewhat greater than the length, and measures 2*3 mm ; the shape of this species is 
therefore quite characteristic. On the margin are twenty cirri, the last pair of which 
are more distant from each other than the others. The bases of the cirri are broad, 
with a number of annular folds ; the whole margin of the body is feebly excavated at 
intervals. The length and breadth of the cirri in the two individuals that I examined, 
was quite different. In the one (fig. 13) they reach *09 mm., in the other *16 mm. 
The parapodia are situated near the margin of the body (fig, 11), but are feebly 
developed ; the short basal portion lies in a flat cavity, and the thin terminal part alone, 
which measures *2 mm. and is often curved, is visible beyond it. The suckers are still 
nearer to the margin, and just as little developed. On the dorsal surface is a sharp keel, 
and on the ventral side, corresponding to it, is a more obtuse and less prominent keel 
(fig. 14). There is no trace of the central ventrally placed elevation, and as the pharynx 
also is marked on the outside by no elevation, it may be safely concluded that it is of 
small dimensions. I discovered the mouth after a laborious search ; it is a fine slit on 
the bottom of the anterior notch of the body, and looks forwards and downwards ; its 
margin is not at all thickened., The cloaca! aperture is still more minute, and lies at the 
hindermost extreme of the body. 
