OPHIUROIDEA 



181 



(Fig. 101, d). Moutli papillae two on each side of jaw, turning 

 somewhat outwards. Arm spines 6-8, usually 7, the lower one 

 sUghtly the longer. Disk up to ca. 12 mm. in diameter ; arms 

 very long, ca. seven times the diameter of the disk, somewhat 

 thicker farther out than at their base. Colour in life reddish- 

 brown, finely spotted with white. Arms more or less distinctly 

 banded. The arms very easily break off, and also the whole 

 disk is easily thrown off. 



It prefers a hard bottom, where it conceals itself in all sorts 

 of crevices ; at Plymouth it is especially found in old crypts of 

 Pholadids. Development unknown ; at Plymouth its gonads 

 were found to be ripe in August. 



In British seas this species has been recorded only from off 

 Plymouth (Mewstone Ledge, Stoke Point Grounds) in 27-36 

 metres. It is elsewhere distributed from the Channel to the 

 Moroccan coast, the Azores, and the Mediterranean. The bathy- 

 metrical distribution is ca. 25-185 m. 



2. Ophiopsila annidosa (M. Sars). (Fig. 102.) 

 (Syn. Ophianoplns annulosa M. Sars.) 

 Very much like the preceding species, but easily distinguished 

 from it by the radial shields being wholly covered by the 



Fig. 102. — Ophiopsila annulosa ; part of arm, ventral side (a), and in side 

 view (6). X 6. (After Koehler, Faune de France.) 



fine scaling so as not to be visible externally, and by the 

 more numerous arm spines, Avhich are generally twelve ; the 

 lowermost are the longest. 



