CHARACTERISTIC DEKP-SEA TYPES. 



OPIIIURANS. 



109 



North of Cape Hatteras the species of starfish procured by the 

 "Blake" are identical with those described by Professor Verrill 

 from the dredsfin^'s of the United States Fish Commission. 



I would only mention here, as the most interesting of the 

 sjDecies we found, ten-armed specimens of Brisincja coronata. 

 (Fig. 387.) This species forms the subject of an elaborate 

 paper by the younger Sars, and I have here reproduced one of 

 his figures. 



OPHIURANS.^ 



Among Echinoderms there are two families, the brittle-stars, 

 or Ophiuridae, and the branching-stars, or Astrophytidae, which 

 are distinguished by a peculiar axis in the arms, made up of 

 articulated bones somewhat like vertebrse. The disk or body is 



Fig. 389. — Ophiocreas spinulosus. •^. 



usually distinctly set off from the arms. These last contain no 

 prolongation of the central digestive cavity, as they do in the 

 starfishes proper. 



' Mr. Lyman has prepared the account of the ophiiirans. 



