172 



ECHINODERMS OF THE BRITISH ISLES 



cold area of the Faroe Channel is very remarkable, and needs 

 verification. 



Fig. 9G. — Ophiophrixus spinosus ; arms cut off near base. 

 (After Bell, Classifw. Ophiuroids.) 



Nat. 



Fig. 97. — Ophiophrixus spinosus. Part of oral side (1), of ventral (2), and 

 dorsal side of arm (3) ; skin removed so as to show the plates distinctly. 

 1. X 4; 2-3. X 8. (After Th. Mortensen, Echinod. Trondhjem Fjord.) 



II. Family Ophiotrichid^ 



Disk with weU-developed scales, which may be more or less 

 concealed by small spines or thorny stumps. Radial shields large. 

 Both dorsal and ventral arm plates well developed. No mouth 

 papillae, but a group of tooth papillae, and inside these a series of 

 broad, strong teeth on apex of jaws. Second pair of tube-feet 

 inside the mouth edge. Spines erect, generally distinctly thorny- 



