312 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Ophiocoma pumila Liitken. 



Ophiocoma riisei Liitken. 



Ophiocoma schonleini Miiller and Troschel. 



Ophiocoma scolopendrina Lamarck. 



Ophiocoma valenciae Miiller and Troschel. 



Ophiocoma variegata Smith. 



Ophiocoma xoendtii Miiller and Troschel. 



I have not included in this list Ophiocoma papillosa Lyman from 

 California, which really belongs to the genus Ophiopteris, nor O. 

 variabilis Grube, which is not recognizable and which Lyman sup- 

 poses to be O. schonleini. 



Ophiocoma echinata, O. pumila, O. riisei, and 0. marmorata be- 

 long to the Atlantic Ocean ; 0. marmorata is recorded by Marktanner 

 as coming from a locality situated in the middle of the Atlantic; 

 this is evidently an error. Among the other species 0. brevipes, 

 O. erinaceus, O. lineolata, O. scolopendrina, O. doderleini, 0. schon- 

 leini, 0. valenciae, and O. wendtU belong to the Indo-Pacific region, 

 and the four first species are very common there. The others have 

 been found less frequently and appear to have more restricted habi- 

 tats. Ophiocoma aethiops and 0. dlexandri come from the Pacific 

 coast of Central America and California; O. canaliculata has only 

 been met with in Australia, and O. bollonsi in New Zealand. Ophio- 

 coma brevispina and O. variegata, collected at the island of Rodri- 

 guez, are perhaps only forms of 0. brevipes. Ophiocoma hibrica 

 comes from the Laccadive Islands, and 0. insularia from the 

 Hawaiian Islands. 



In regard to these different species I have the following notes : 



Ophiocoma doderleini. — In 1915 H. L. Clark gave 0. doderleini 

 as a synonym of O. brevipes; I do not share that opinion. I shall 

 discuss further on in speaking of O. brevipes the characters which 

 distinguish this latter from O. doderleini. 



Ophiocoma aethiops. — This species is known from the descriptions 

 of Liitken ('59, p. 145) and of Lyman ('65, p. 78) ; very recently 

 H. L. Clark has published two photographs of it ('15, pi. 13, figs. 

 6, 7). Lyman has already described the variations shown by 0. 

 aethiops regarding the number of the tentacle scales and the develop- 

 ment of the granules on the ventral surface of the disk. The ten- 

 tacle scale is usually single, and it is only double on the two first 

 arm segments ; but often two tentacle scales occur over a large number 

 of successive segments, and I have in my collection specimens from 

 Panama in which the tentacle scales are two in number on most of the 

 arm segments as far as the twentieth. In these specimens the granules 

 only extend over a very restricted portion of the ventral surface of 

 the disk. The mouth shields, which are hexagonal in form, are very 

 much longer than broad, and they may even be almost twice as long 



