OPHIUROIDEA 



247 



1. Ojyhiocten sericeum (Forhes). (Fig. 134.) 



(Syn. Ojihiocten Kroyeri Ltk. ; 0. ahyssicolum (Forbes) ; Ophio- 

 glyi^ha gracilis G. O. Sars ; Ophiocten Le Danteci Koehler.) 



Disk covered with numerous very fine scales, among which 

 the primary plates are very conspicuous ; in large specimens the 

 small scales almost have the character of small granules ; in 

 young specimens the primary plates are surrounded only by a 

 single circle of small plates. Radial shields narrow, widely 

 separated, about J the disk radius. Arms ver}^ distinctly roof- 

 shaped. Dorsal plates of arms broader than long, the outer edge 

 slightly convex ; the proximal dorsal plates carry a series of fine 

 papillae along their outer edge ; in larger specimens these papillae 

 may be found to the 15- 16th arm- joint ; in young specimens 



Fig. 134. — Ophiocten sericeum (Forbes) ; part of oral (1) and dorsal side (2). 

 X 4. (From Danmark's Fauna.) 



they are only feebly developed, or may even be totally lacking. 

 The papillae along the edge of the disk above the base of arms 

 may be confined to a smaU group at each side (corresponding to 

 the outer comb in Ophiura). Ventral plates very smaU, with 

 convex outer edge and a small, very obtuse proximal angle ; they 

 are widely separated. Three slender arm spines, about equally long, 

 in the proximal part of arm slightly longer than an arm -joint. 

 One small tentacle scale, the proximal 2-3 pairs, also with a small 

 scale at the outer edge of the pore. Mouth shields scarcely 

 longer than broad ; 4-5 mouth papillae on each side of jaw, the 

 outer one broad, scale-like. Colour in life, bluish-grey to dark 

 violet, nearly black ; arms lighter. Grows to a size of ca. 18 mm. 

 diameter of disk. Arms ca. four times as long as diameter of 

 disk, rather slender and fragile. 



Development unknown, but judging from the small size of 

 the eggs it may be expected to have pelagic larvae. Possibly 



