REPORT OH THE M YZOSTOMID A. 
41 
becomes larger towards the margin, and bulges slightly forward. In the middle of the 
outer extremity of each of these is a smah conical tubercle — the parapodium — which is at 
the most '1 mm. long. The third sector is slit on both sides by a secondary furrow, 
in which hes the parapodium as well as the male genital aperture ; there are two fine 
tubercles also occupying the tip of the secondary prongs. The flat suckers are at the 
external margin of the ventral elevation, in the chief furrows and closer to the dorsal 
portion. Just beneath the marginal zone of the dorsal disk are the mouth and cloacal 
apertures. The long pharynx is much extended forwards and flexed towards the dorsal 
aspect. The ventral surface is rather lighter in colour than the back, and not so smooth, but 
divided by shallow furrows into a number of polygonal areas about - 07 mm. in breadth. 
Host . — The single specimen was found on an Actinometra, closely allied to, if not 
identical with Actinometra meridionalis, A. Ag., dredged by Capt. Werner in 1873, 
near Barbados ; it belongs to the Kiel Museum. 
22. Myzostoma pulvinar, Graff (PI. III. figs. 21-23). 
Myzostoma pulvinar, Graff, Proc. Roy. Soc. Edin., vol. xii. p. 379, 1884. 
This species, of which I possess only one specimen, is very much like Myzostoma radi- 
atum; the dorsal surface in both species is flat and the ventral surface vaulted. The oral 
and cloacal apertures, however, differ in being on the dorsal surface. This latter is formed 
by a transversely oblong plate, marked off sharply from the rest of the body ; the margin 
of which is bent upwards in front and at both sides, but downwards behind (fig. 21). 
The diameter of this dorsal disk, which is quite smooth, save for the reflected portions 
that are slightly wrinkled, is 3 '2 mm., the length 27 mm. The obtusely pointed cloacal 
papilla is ‘45 mm. distant from the hinder end of the body ; the mouth has a thick lip, and 
is not so far from the anterior end of the body as the cloacal papilla. The massive 
pharynx protrudes from the mouth. The body is of a firm consistency ; the colour is a 
uniform yellowish-brown. 
This species is thicker in proportion than any other ; there is only a narrow marginal 
zone not occupied by the hugely developed ventral elevation. The anterior and pos- 
terior borders of this elevation are parallel, the distance between them being 2 '3 mm.; 
the sides are rounded, the transverse diameter being 3 ‘4 mm. The ventral elevation is 
distinctly marked off from the dorsal disk by its considerable cross extension, and it is 
very prominent when observed from above. 
The parapodia arise from the margin of the ventral elevation ; the anterior pan being 
situated at the junction between the straight anterior and the rounded lateral margin. 
The parapodia are at equal distances from each other, and it is only the last pair which are 
separated by a somewhat wider interval. The parapodia appear as if they were almost 
immovable; the hook apparatus is strongly developed and projects greatly; in the 
specimen that I examined it projected '2 mm., and even the point of. the manubrium came 
(ZOOL. CHALL. EXP. PART XXVII. 1884.) Dd 6 
