OPHIUEANS OF THE PHILIPPINE AND ADJACENT WATERS. 237 



small ; they show on their concave border behind the terminal point 

 a series of from six to eight very elongated points, which are narrow 

 and arranged parallel to each other. The terminal point is not ap- 

 preciably larger than the others, and is even sometimes smaller than 

 the second (fig. 2d). On the convex border and toward the tip are 

 a few unequal and irregular asperities. This form of hook recalls 

 that which I have described in 0. expedita, and which we find again in 

 O. propinqua and O. puncto-limbata; it is very different from that 

 which we know in the majority of the species of Ophiothrix, and 

 which occurs in O. Mrsuta. It is to be noticed also that the difference 

 between this hook and the second ventral spines is not very great 

 In figure 2c I show the first ventral spine at a short distance from 

 the disk, where it has not yet acquired the definitive form of a hook 

 provided with regular points. The tentacle scale (l>) is oval and 

 terminated by a long point. 



Ophiothrix longipeda has been met with in a large number of 

 localities in the Indo-Pacific region. 



I have continued to consider as different species O. gdlatheae, 0. 

 Mrsuta, and O. longipeda, and in fact the specimens included in the 

 Albatross collection can be perfectly well and easily assigned to one 

 or the other, their characters being well marked. It is not worth 

 while to review their characters here, nor those of 0. puncto-limbata 

 which I enumerated and discussed in 1905 ('05, pp. 94, 95). But I 

 have thought that it might be useful to include some photographs 

 which will facilitate the determination of these forms. To the 

 species brought back by the Albatross I have added (pi. 32, fig. 6) 

 a photograph of the dorsal surface of an O. puncto-limhata / the speci- 

 men came from Amboina and was given me by Professor de Loriol ; 

 it is one of those which he described in his memoir of 1893 (p. 416). 

 I have added to the photographs showing the dorsal surfaces of the 

 arms of various species of Ophiothrix (pi. 33) one of an O. obtusa, 

 the upper arm plates of this species recalling those of certain forms 

 of O. Mrsuta, which it likewise approaches in the armature of the 

 dorsal surface of the disk; but O. obtusa is easily distinguished from 

 the O. galatheae-Mrsuta-longipeda group by its very short arms. 



In his recent catalogue of the living ophiurans H. L. Clark wrote 

 in regard to O. rhabdota ('15, p. 278) that he strongly doubted the 

 validity of 0. gdlatheae, O. Mrsuta, and O. puncto-limbata, and he 

 believed that further studies would lead without doubt to uniting 

 them with O. longipeda, while 0. expedita, on the other hand, ap- 

 peared to him better characterized. For the moment, I can not share 

 the opinion of the learned American naturalist, and, after having 

 had occasion to study a rather large number of Ophiothrix belong- 

 ing to the species named above, I do not see my way clear to unite 

 certain of them with O . longipeda. To be sure the characters on 



