120 THE ECHINODERMS OF TORRES STRAIT. 
correspondingly stout arm-spines, well-developed oral papille and distinct clusters of dental 
papille at the point of each jaw. It approaches the Ophiodermatide in many ways, and 
the line between the two families is not a conspicuous one. Both Lyman and Litken, the 
two ablest students of ophiurans in the past century, regarded the genus Ophiarachna as one 
of the Ophiocomide, whereas there seems no reasonable doubt now that its true place is 
with the Ophiodermatidz. The absence of dental papillee would seem to be conclusive. 
With Ophiarachna left out of account, the Ophiocomide includes but 5 genera, of 
which Ophiocoma and Ophiopsila are nearly or quite tropicopolitan, though Ophiocoma is not 
known from the Mediterranean and Ophiopsila has yet to be found in the Eastern Pacific. 
Ophiomastix and Ophiarthrum range from Zanzibar to the Society Islands, and even to the 
Paumotus, but strangely enough, neither genus is yet recorded from Hawaii. Ophiopteris 
has a peculiar distribution confined to the Pacific. Ophiopsila differs so noticeably from the 
other four genera that Matsumoto (1917) makes it the basis for a separate subfamily. There 
are 11 species, which have recently been the subject of a revision (H. L. Clark, 1918). 
The subfamily Ophiocomine needs similar treatment, and, as suggested above, the present 
report seems a suitable place for the publication of the results. The four genera may be 
distinguished from each other as follows:! 
Key to the Genera of Ophiocomine. 
Disk covered with scales, sometimes imbedded in the skin, which bear more or less numerous granules or 
spinelets or both; often the scales are more or less fully hidden under the coat of 
granules. 
Disk covered with granules, which normally conceal the underlying scales, except often in the 
interbrachial ares below;* no true disk spinelets; claviform arm-spines exceptional. 
Uppermost arm-spines not evidently shortened and flattened, but often considerably enlarged... Ophiocoma 
Uppermost arm-spines on each side of each joint (and on basal part of arms in large speci- 
mens, second spine also) modified to form a flat, elliptical or circular scale......... Ophiopteris 
Disk with more or less evident spinelets, in some species with granules also; some upper arm-spines 
more orlessyclawiforrmtsersepee 5 cio eve ees aise aio ore oe Eero Tots ots Seok ete ee Ophiomastiz 
Disk covered with a smooth, naked skin, bearing neither granules nor spinelets...................05 Ophiarthrum 
OPHIOCOMA. 
L. Agassiz. 1835. Mem. Soc. Sci. Nat. Netichatel, 1, p. 192. 
This is the largest and most widely distributed genus of the family, species occurring in 
all parts of the tropics, except only the Mediterranean Sea, into which nospecies has yet pene- 
trated. It is true that Ophiocoma nigra (Retzius) and Ophiocoma tumida Miller and Troschel 
are both listed from the Mediterranean, but the former is one of the Ophiacanthide, not one 
of the Ophiocomide, and the specimen on which twmida is based seems to be an individual 
of O. echinata and surely did not originate in the Mediterranean. The northern limit of 
Ophiocoma in the Atlantic is at the Bermudas and in the Indo-Pacific region is in or near 
Kagoshima Gulf, Japan. Thus no species is known from above latitude 34° N. In the 
southern hemisphere the range is somewhat greater, reaching at least latitude 40° S., dif- 
ferent species occurring along the South African coast, on the southern coast of Australia, 
and between the main islands of New Zealand. In the West Indies there are 3 species, all 
abundant and widely distributed; one of these, at least (pumila), ranges clear across the 
Atlantic, having been taken not only at the Cape Verdes but at the islands in the Gulf of 
Guinea and even on the French Kongo coast. In the Paris Museum there is a specimen of 
one of the other species (echinata) said to be from the coast of Liberia, and there is no 
improbability of its occurrence there. Two species occur on the west coast of Central 
America and Mexico; neither is known from anywhere on the South American coast, but 
one occurs at the Galapagos Islands. Throughout the Indo-Pacific region, from 4 to 6 
species may be found wherever conditions are favorable. 
‘ Yor genotypes, lists of species, localities, and other data see H. L. Clark, 1915, Mem. M. C. Z., 25, p. 290-297. 
*In specimens which have been roughly handled, the granules may be rubbed off from a large part of the 
disk, leaving the scales quite visible. Such specimens are often very perplexing. 
