OPHIUROIDEA 177 



diameter of disk and an arm length of ca. 150 mm. Colour in 

 life pinkish, often with radiating whitish bands on the disk ; 

 arms generally banded with pinkish and whitish. 



Development and biology unknown. 



In British seas this species is common in deeper water off 

 S.W. Ireland, in depths of ca. 150-500 m. ; also recorded from 

 the Lousy Bank, and likewise known from oif the Shetland 

 Islands.^ It has elsewhere been found in the Bay of Biscay, 

 where it is very common, between the Canaries and Cape Verde, 

 and off the Azores. Bathy metrical distribution ca. 50- ca. 500 m. 



III. Family Ophiocomid^ 



Disk mostly covered with granules, which conceal both the 

 scales and the radial shields. Both dorsal and ventral plates well 

 developed. Arm spines erect. Mouth papillae present. Each 

 jaw carries a group of tooth papillae and below these a series of 

 strong teeth. Second pair of tube-feet inside the mouth edge. 



Two genera of this family represented in British (and 

 European) seas. The main genus of the family, Ophiocoma, so 

 characteristic of the littoral region of tropical seas, is not repre- 

 sented in European seas, the statements in older literature of the 

 occurrence of " Ophiocoma tumida " Miill. and Troschel in the 

 Mediterranean resting on mistakes. 



Key to the genera of Ophiocomidce found in British 

 and European seas. 



Disk granulated ; tentacle scales simple 1. Ophiocomina Koehler 



Disk not granulated ; inner tentacle scale much elongated, flattened, 



crossing that from the opposite side on the middle of the ventral 



surface of arm (Figs. 101, a, 102, a) . 2. Ophiopsila Forbes 



1. Ophiocomina Koehler. 



Disk completely covered by small granules. Arm spines 

 simple, rather delicate, hollow, none of them especially elongate 

 or club-shaped. Tentacle scales simple, none of them especially 

 transformed. Teeth without a hyaline enamel-like cap. 



Only one species in British and European seas, the only species 

 known of this genus. 



^ The statement of the occurrence of this species off the Shetland 

 Islands rests on information from Grieg that it was taken at the following 

 localities by "Michael Sars " : 61° 3' N.. 2° 13' E., 130 m. ; 61° 52' N., 

 1° 8' E., 220 m. ; and 61° 43' N., 1° 16' E., 190 m. 



