ANNOTATED LIST. 119 
Torres Strait and from the Philippines, I find the truth is that Déderlein’s species is per- 
fectly valid and can be readily distinguished from dubia by the skin-covered adorals and the 
shape of the arm-plates. In semoni, the disk-scaling is reduced to a minimum and the soft 
skin of the oral side not only conceals or at least obscures the outlines of the oral shields and 
adoral plates (even in young dried specimens), but it softens, and may even obscure the 
outlines of the basal under arm-plates. In dubia, the basal under arm-plates, oral shields, 
and adoral plates are well-defined and there is no evidence of a thick skin. In semoni, the 
upper arm-plates are relatively long and narrow, while the proximal lateral angles are ap- 
proximately 60° to 70° (see Déderlein’s fig. 8a), but in dubia these plates are shorter and wider 
and the lateral angles are about 45° to 50°. In semoni the under arm-plates are markedly 
bell-shaped, much wider distally than proximally (see Déderlein’s fig. 8), while in dubia they 
have nearly parallel lateral margins. These differences seem to me ample to distinguish the 
two species, but they do not warrant a generic difference and therefore, like Liitken and 
Mortensen (1899) and Koehler (1905), I reject Déderlein’s proposed genus Ophiotriton. 
The degree of development of the scales in the disk skin in dubia shows considerable diver- 
sity; in some dry specimens, scales are well-developed and show clearly under a lens, while 
in other cases they are small and hard to make out. So, too, in semoni, while the scales are 
usually so small and so embedded in the skin that they can be detected only with a micro- 
scope, in some well-preserved specimens they are more easily visible. 
It is evident, then, in the light afforded by the material at hand, that in Torres Strait 
we have an Ophionereis quite distinct from the Indian Ocean species dubia. A specimen I 
took at Green Island near Cairns, Queensland, is undoubtedly semoni, as are specimens we 
collected at Friday Island and Badu. The last is a fine specimen with disk 7mm. across and 
arms 40 mm. long. The Torres Strait specimens are variegated with dull green and cream- 
color or whitish, but the one from Green Island is pale yellowish and dull light purple. In all 
cases the arms are distinctly banded. These brittle-stars were found under rock fragments 
on sand. It is notable that not a single specimen was found at Mer. Of course, the ophion- 
ereids taken by the Alert and listed by Bell, without comment, as O. dubia, are really 
O. semoni. 
The range of semoni to the north and west is doubtful because it is evident that Koehler 
has not clearly distinguished it from dubia. In his report on the littoral ophiurans of the 
Siboga he lists semoni from 9 stations and makes no reference to dubia. But his figures (pl. 
vi, figs. 7, 8) show conclusively that they were made from a specimen of dubia. As our 
Philippine specimens are dubia, and most of the Siboga material is from the western and 
northern part of the East Indies, I am inclined to think probably the Dutch expedition did 
not meet with semoni, though the specimens from stations 282 and 301 might be that species. 
It is less easy to decide about the specimens Koehler has listed (19072) from Sharks Bay, 
Western Australia, and (1910) from the Aru Islands, as O. dubia. There is no a priori reason 
why they may not be that species, but I feel suspicious that they are really semoni. 
OPHIOCOMID¢£E. 
The members of this family are by far the most abundant, most noticeable, and most 
interesting brittle-stars on the reef-flats in Torres Strait. Their large size, conspicuous color- 
ation, and notable activity attract constant attention. All are shallow water forms, but 
many show an adaptation to a particular habitat that is quite marked. The family is a 
relatively small one, and is so well defined that a revision of its constituent members is not 
a great task, and, since they form about one-fifth of the ophiurans of the Torres Strait re- 
gion, it is fitting that such a revision should be offered here. Members of the family occur 
in the West Indian region and in the Eastern Pacific, but the East Indies is its obvious home 
and a large percentage of its members occurs there. The family is easily recognized by the 
combination of a disk usually granulated but sometimes bare, flattened, stout arms with 
