204 ECHINODERMS OF THE BRITISH ISLES 



In British seas this species has been found only in the Faroe 

 Channel (60° 25' N., 8° 10' W., 690 m., " Porcupine "). Else- 



FiG. 115. — Ophiopus arcticus ; part of oral (upper figure) and dorsal side 

 (lower figure). x 15. 



where known from the Norwegian coast to Spitzbergen, Iceland, 

 and Greenland. Bathymetrical distribution ca. 50-ca. 1200 m. 



3. Ophiopholis Miiller and Troschel. 



(Syn. Polypholis Duncan.) 



Disk with granules or spinelets which cover the scales, but 

 generally leave the primary plates naked and very distinct. A 

 circle of small plates surrounds the dorsal plates of the arms. 

 The lower arm spine hook- shaped in distal part of arm. Genital 

 slits well developed. 



Only one species in the British (and European) seas. 



1. Ophiopholis aculeata (Linn.). (Fig. 116.) 



(Syn. Ophiocoma bellis Forbes ; Ophiopholis hellis Lyman ; 

 Polyj^hoUs echinata Duncan.) 



Disk with granules, often with small spines scattered among 

 them, leaving the primary plates naked ; these latter generally 



