Xo. 6. — Brittle-Stars, Xew and Old. 

 By Hubert Lymax Clark. 



SixCE the publication in December, 1915, of the catalogue of 

 brittle-stars in the IMuseum collection, (Mem. M. C. Z., 25) there have 

 been considerable accessions, including a number of species apparently 

 undescribed. These accessions have come chiefly from four sources : — 

 (1) Mr. Joseph Gabriel, Melbourne, has continued his generous 

 donations of echinoderms from the coast of Victoria; (2) Dr. I^awrence 

 E. Griffin, Pittsburgh, formerly of ^Manila, presented a large series 

 representing 38 species from the Philippine Islands; (3) the present 

 writer collected nearly fifteen hundred specimens of 36 species at Pigeon 

 Point, Tobago, in March and April, 1916, while working in the 

 Carnegie Institution's marine laboratory at that place; (4) a similar 

 collection of 36 species was made at the Tortugas, Fla., in June, 1917, 

 while at the Carnegie Institution's laboratory on Loggerhead Key. 

 Thanks are herewith extended to Dr. Alfred G. Mayer for the oppor- 

 tunity of making these two collections and for permitting the publica- 

 tion of this account of the more important species obtained. 



While identifying the specimens of Ophiophragmus, Ophionephthys, 

 Ophiactis, and Ophiopsila from Tobago and the Tortugas, it became 

 necessary to make a careful revision of the previously known species 

 in those genera and the results are published here. I therefore give 

 artificial keys and a full synonymy, accompanied by a statement of 

 the geographical distribution of each accepted form. 



OPHIACANTHIDAE. 



Ophiacaxtila oligacax'tha, sp. nov. 



oXLyos = few + aKavOa = a spine, in reference to the small number of 



arm-spines. 



Plate 7, fig. 5. 



Holotype. — M. C. Z. 4,214. Florida: Dry Tortugas, Garden Key, 

 June, 1917, in coralline Algae along shore. Carnegie Expedition. 

 H. L. Clark coll. 



