48 
conspicuous, especially when standing erect; in specimens not dried 
they are seen to support a small triangular flap of skin covering 
the base of the tentacle at its proximal side. Furtber the disk 
of O. purpurens is set with scattered, small spines, while 
in glacialis it is entirely smooth. In alcoholic specimens these 
spines are hard to see, but I have found them quite constantly in 
dried specimens, though in varying numbers. Also the radial shields 
are longer and more developed in pnrpiireus than in glacialis 
(Figs. 1, d, e). — In the internal anatomy there seems to be no 
essential difference between the two species. 
O. glacialis grows to a much larger size than purpureus ; the 
largest specimens of the former species at my disposal measure 
ca. 35 mm in diameter of disk, while the largest specimens of 
purpureus that I have seen. measure only ca. 15 mm in diameter 
of disk. 
The presence of spines on the disk of O. purpureus approaches 
this species to the genus Ophiobgrsa and makes it doubtful, 
whether the latter can really be maintained as a separate genus. 
This, of course, sounds rather paradoxical, since Ophiobgrsa is 
regarded in modern classification of Ophiurids (Matsumoto) as the 
type of a separate subfamily, Ophiobyrsiuæ, of the family Ophio- 
myxidæ, the difference between the two subfamilies even being 
regarded as „very sharp“. Nevertheless, I think I am right, and 
the supposed differences between the two subfamilies appear to 
me rather unessential and confluent. At present, I cannot, how- 
ever, enter on a detailed discussion of the question, — also for 
the reason that the material of Ophiobgrsa and related genera 
available is rather unsatisfactory. 
2. Ophiomitrella clavigera (Ljungman) (Fig. 2). 
The species described by Ljungman under the name of 
Ophiactis clavigera was shown by Liitken 1 ) to have nothing 
to do with the genus Ophiactis , its true affinities being with the 
genus Ophiacantha. Thinking that this species might possibly be 
identical with O. Fr. Miiller’s „ Asterias tricolor u , he then named 
it Ophiacantha tricolor (Abgd.). The latter identification, however, 
X J Liitken. Additamenta ad hist. Ophiuridarum. III. p. 32 (50). 
