46 
THE VOYAGE OF H.M.S. CH ALLEN GEE. 
Host. — (a) Metacrinus costatus , P. H. C., n. gen. and sp., from Station 214 (south of 
Philippine Islands) of the Challenger Expedition (500 fathoms). 
(b) Another specimen was found by Mr. Carpenter attached to the anal tube 
of Metacrinus angulatus, P. H. C., n.. gen. and sp., from Station 192 
(south-west of Papua) of the Challenger Expedition. It was 3 mm. in 
length, and the bulbus musculosus of the pharynx measured ‘9 mm. in 
length. 
31. Myzostoma vastum, n. sp. (PI. VII. figs. 2, 3). 
The four specimens which I examined came from Actinometra japonica, and belong to 
the Leyden Museum. They are characterised by the smallness of the marginal border, due 
to the extension of the- intestinal caeca (i.) and the ovarian follicles (ov.) nearly as far as the 
margin, and by the larger size of the twenty cirri. The first, second, ninth, and tenth 
pairs of cirri are the longest, especially the ninth, which in the specimen displayed in 
fig. 2, measure ’6 mm. in length and ‘068 mm. in diameter at the base.. The third and the 
eighth pairs are the shortest, and measure no more than ‘2 mm. The large oval flat 
suckers (s.) stand at the same level as the ends of the parapodia ; the parapodia are 
strongly developed. The cloacal aperture (cl.) lies at the same height as the external 
margin of the suckers, but the oral aperture is beneath the anterior margin when the 
pharynx is contracted. In the specimen figured, however, the pharynx is extended, showing 
its crown of papillae, and so the appearance is different, sinee the mouth opening is so much 
enlarged that its posterior margin is withdrawn further inwards into the disk of the body. 
The colour of the animal is lightish brown, inclining to yellow towards the margin ; 
the body is about as thick as in Myzostoma cirriferum. The largest specimen measured 
1 '7 mm. long by 1'47 mm. broad. In one individual the dimensions of the cirri were 
somewhat different from the description given ; the last pair appeared to be extremely 
shortened, shorter than the lateral cirri, and one had an abnormal lateral branch (fig. 3). 
Two smaller specimens, dredged during the “ Blake ” Expedition, appeared from their 
general configuration to belong to this species. The ten pairs of cirri were of equal 
length, and arranged at equal distances from each other; one specimen (host uncertain) 
was *7 mm. in length, with cirri of '056 mm. in length ; the other (from Actinometra 
meridionalis ) was ‘97 mm. in length, and the cirri T36 mm. The last specimen had 
its pharynx fully extended and crowned with a circlet of papillae. 
Host. — (a) Actinometra japonica, M till. , sp., from the Leyden Museum. 
(b) Actinometra blaJcei, P. H. C., from Station 39 of the “ Blake ” Expedition. 
The same species of Myzostoma was also found in the bottle contain- 
ing the Crinoids collected at Station 203 of the “ Blake ” Expedition. 
The fact that Actinometra blakei occurred in this bottle, probably shows 
that it is to be considered as the host of this Myzostoma , 
