50 
figures, the somewhat more globular shape of the stumps on the 
disk in cordifera and the different form of the oral shield and the 
dorsal plates. The latter, however, are rather variable in clavigera , 
in some specimens (notably in 
one of Ljungman’s cotypes 
from the Skagerrak) very dis- 
tinctly rhombic, in others with 
the outer border more rounded. 
The oral shield I have never 
seen exactly of the shape given 
by K o e h 1 e r for cordifera , but 
it is also rather variable in shape, 
often quite irregular. Also the 
length of the spines varies to no 
small extent, thus in the cotype 
mentioned they aredistinctlyshort- 
er and thicker than in the spec- 
imen figured here (from Green¬ 
land). The stumps on the disk 
I have never seen so globular 
as Koehler figures them, but I would not be inclined to think 
that character alone a valid specific difference. I am therefore very 
much inclined to think that O. cordifera will prove to be identical 
with clavigera. — I would suggest also the possibility that Ophio- 
lebes acanellæ Verrill is identical with O. clavigera. From the de- 
scription given by Verrill it is impossible to see how it is to be 
distinguished from that species; but as no figures have, so far as 
I know, been published of O. acanellæ , nothing can be said defin- 
itely about the question. 
As I have shown in my paper on „Hermaphroditism in vivipar- 
ous Ophiurids“ l ) this species is viviparous and, besides, a proter- 
andric hermaphrodite. Moreover, it is interesting in being the host 
of a very remarkable (as yet undescribed) parasitic Crustacean, 
probably a Copepod, with 4 egg sacs. The specimens infested by 
the parasite are totally castrated by it. 
3. Ophiocomina nigra (O. F. Muller). 
It was pointed out by Ly man (Challenger-Ophiuroidea. p. 168) 
that this species, hitherto named Ophiocoma nigra , differs from 
Fig. 2. Ophiomitrella clavigera. 
a. ventral side. b. dorsal side. 9 /i. 
*) Acta Zoologica. I. 1920. 
