REPORT ON THE MYZOSTOM1DA. 
61 
feebly developed in proportion to tlie robust body. Outside the third pair of parapodia 
are the male generative apertures ( $ ), which project as small tubes. I could not find 
any trace of suckers. 
Host. — BatJiycrinus cddrichianus, Wyv. Thoms., n. gen. and sp., from Station 146 
(west of the Crozets) of the Challenger Expedition. 
59. Myzostoma folium, n. sp. (PL III. figs. 10, A, B, C, 11). 
This elegant species is leaf-like in its general form, the anterior part of the body has 
a considerable diameter, which is gradually reduced until it terminates in a blunt point. 
The body is tolerably flat, but there is a slight dorsal longitudinal elevation. The dorsal 
surface is finely wrinkled and brown in colour ; the marginal zone is transparent, 
yellowish in colour, and serrated. 
On the ventral side the central part is even more sharply marked off from the mar- 
ginal zone (A and B). The marginal zone is rather different from the same structure in 
other Myzostomida ; it appears very much as if it were composed of a number of cirri 
fused together. The length of the single specimen is 5 mm., its greatest breadth nearly 
2 mm. In the middle line of the ventral surface is a long narrow elevation running from 
the mouth to the cloacal aperture (cl.), which is distant one-sixth of the length of the 
body from its extremity. The pharynx (ph.) is very large, and extends some distance out 
of the mouth, measuring about one-fifth of the whole length of the body. The parapodia 
( p .) are strong and well developed ; they are arranged in two parallel lines in the anterior 
part of the body. The last pair, however, are closer together, and arise quite near 
the median elevation. Each parapodium is divided by a circular furrow into 
a larger basal portion and a longer, but thinner, terminal part. On the latter there 
is a deep ventral furrow. In fig. 11 is shown the termination of one of the hooks. The 
point is somewhat bent and very strong ; it shows upon its concave side a flat furrow ; 
there was no trace of any suckers. 
Host. — Antedon manca, P. H. C., Station 192 (south-west of Papua) of the Challenger 
Expedition. 
60. Myzostoma asymmetricum, n. sp. (PI. XI. figs. 4-8). 
Mr. Herbert Carpenter observed a portion of an arm of Pentacrinus alternicirrus, two 
of the pinnules of which were larger than the rest ; this portion is drawn from the side 
on fig. 4 B, which shows that these pinnules are twice as large as any of the others. The 
arms themselves are also slightly swollen in the neighbourhood of these pinnules ( # ), as 
may best be seen from the dorsal surface (A). On examining it, a yellowish coloured 
Myzostoma was found on the inner side of the enlarged pinnule (fig. 5). The parasite 
was not attached to the ambulacral side of the pinnule, though close to it, and the pinnule 
