CLARK: JAPANESE AND EAST INDIAN ECHINODERMS. 299 



far up on sides of slit. Teeth papillae four to six, first or second much larger and 

 more acute than others. Teeth few, apparently only five or six, thick, rounded 

 triangular. — Ventral arm-plates small, separated by rather stout side arm-plates 

 which meet in midline. Tentacle pores very large, diameter equal to or exceeding 

 distance between two consecutive pores ; buccal pair without scales but surrounded 

 by a sprinkling of minute granules ; first pair on arm much smaller than others 

 and with no tentacle scale ; second pair with one tentacle scale ; succeeding pores 

 each with a pair of scales. Tentacle scales tapering, rather acute, and more or 

 less spiuulose at tip ; outer one somewhat shorter than inner, but difference be- 

 tween them is not great on any part of arm ; inner one, where longest, is not 

 equal to two arm-joints. Above outer tentacle scale, on each side of every joint 

 until nearly at tip of arm, is a low, rounded tubercle. — Color pale reddish. 



1 specimen (dry). Sea of Idzu, Hondo, Japan. Owston collection. 



In the large size of the tentacle pores as well as in general appearance, this 

 species is very similar to 0. japonicus Koehler, but the presence of oral papillae 

 and of granules on the disc, as well as the short nearly parallel genital slits, are 

 such important differences that it does not seem possible that the two can be 

 identical. It must be granted, however, that specific differences in the genus are 

 very slight, and it is by no means certain that the species now recognized are all 

 valid. It seems to be useless to lay any stress on relative proportions of disc and 

 arms, for, as Lyman long ago pointed out, these vary greatly with age. Moreover, 

 the enlargement at the base of the arm, supposed to be characteristic of oedipus, 

 appears to be essentially dependent on the condition of the reproductive organs 

 and therefore of very uncertain value. Bearing these facts in mind, I have pre- 

 pared the following list of, and key to, the species of Ophiocreas. The key shows 

 not only the relationships of the new form herein described, but reveals the re- 

 markably slight differences by which the various species are distinguished from 

 each other. 



List of the species of Ophiocreas. 



lumbricus Lyman, 1869. Bull. Mus. Comp. Zool., 1, p. 347. Atlantic Ocean, 



off West Indies, 60-5S0 fathoms, 

 abyssicola Lyman, 1879. Bull. Mus. Comp. Zool., 6, p. 64. Pacific Ocean, east 



of Japan, 2300 fathoms, 

 oedipus Lyman, 1879. Bull. Mus. Comp. Zool., 6, p. G5. Pacific Ocean, west 



of Philippine Islands, 500 fathoms; northwest of Halmaheira, 1108 fathoms; 



and Atlantic Ocean, off Ascension Island, 420-425 fathoms, 

 carnosus Lyman, 1879. Bull. Mus. Comp. Zool., 6, p. 63. Pacific Ocean, off 



west coast of Patagonia, 175 fathoms, 

 caudatus Lyman, 1879. Bull. Mus. Comp. Zool., 6, p. 64. Pacific Ocean, off 



Enosima, Japan, 345 fathoms, 

 spinulosus Lyman, 18S3. Bull. Mus. Comp. Zool., 10, p. 2S1. Atlantic Ocean, 



off West Indies, 116-28S fathoms. 



