32 
THE YOYAGE OE H.M.S. CHALLENGER. 
for fear of damaging tlie specimen too much. They are distinguished by being strongly 
bent, and by the blackish colour of the tip. The manubrium ( ma .) is similar to that of 
Myzostoma gigas (PI. II. figs. 4, 6), but is not so large in proportion. The round well- 
developed suckers are without the circle of parapodia, and distant from the margin of the 
body by only one-sixth of the entire radius. The free ends of the suckers of the smaller 
individual are more extended, and reach beyond the margin of the body ; they are 
goblet-shaped, and larger than the parapodia. 
The pharynx is half drawn out and well-developed ; the mouth lies as far from the 
margin of the body as the suckers. The cloacal aperture is dorsal, and lies on a papilla 
situated just anteriorly to the hinder margin of the body. 
Host. — Antedon phalangium, Mull., sp. Dredged in the Minch, August 14, 1869, 
and at Station 13 (off Duncansby Head) (1870), lat. 40° 16' N., long. 9° 37' W., in 220 
fathoms, by the “ Porcupine ” Expedition. 
7. Myzostoma costatum, F. S. Leuckart. 
Myzostoma costatum, Graff, Genus Myzostoma, p. 11, pi. i. figs. 13, 14. 
Professor Haeckel obtained another specimen of this form at Tur near Sinai, which 
is rather smaller than the examples previously described by me, and of a slightly different 
form. It measures nearly 2 mm; in length, the lateral parts are bent ventrally and not 
obliquely sloped from the middle elevation of the back. The breadth is rather greater 
than the length ; the marginal notches are more distinct, the colour yellowish-brown. 
The “ ribs ” are not so distinct as in the specimens from Bohol ; the anterior notch is 
not so marked. 
Hosts. — (cl) Comatula multiradiata, Lam. (many types have been confused under 
this name, the host may be either Antedon savignyi, Mull., sp., or 
Antedon palmata, Mlill., sp.), Red Sea. 
(b) Antedon triquetra, Semper, MS., Bohol (Philippines). 
(c) Actinometra parvicirra, Mull., sp., Bohol (Philippines). 
8. Myzostoma plicatum, n. sp. (PI. III. figs. 16-18). 
The body is 4 mm. long and circular in shape, but the true form is somewhat 
concealed by the sides being turned down. The back is sepia brown, and sculptured 
in a very characteristic manner. Instead of a longitudinal elevation, there is a furrow 
running along the length of the back ; several furrows also run across this, from one side 
to the other. There are a number of crest-like elevations corresponding to the intestinal 
caeca ; these elevations cause the marginal part of the body to appear stouter than the 
central (fig. 18). The thickness of the body is somewhat intermediate between that of 
Myzostoma cirriferum and Myzostoma glabrum. The whole disk is opaque, and the only 
