242 



ECHINODERMS OF THE BRITISH ISLES 



(*' Helga "). It is known elsewhere from the Bay of Biscay, off 

 the Azores and Canaries ; also known from the 8. Atlantic. 

 Bathymetrical distribution, 630-2400 m. 



5. Ophiura rohusta Ayres (Fig. 84, lower part of figure ; 

 Fig. 131, 1-2). 



(Syn. Ophiura squamosa Liitken ; Ophioglypha robusta (Ayr).) 



Scales of disk rather coarse, uniform ; only the central plate 

 distinct, the other primaries usually indistinguishable. Radial 

 shields small, scarcely one -third the disk radius ; they may be 

 in contact at their distal end. Arm combs only feebly developed, 

 usually consisting only of a small irregular group of papillae on 

 each side at base of arm. Notch small, containing only 2 small 

 dorsal plates, the innermost of which may sometimes be slightly 

 heart - shaped. Arms not high, roof - shaped arched. Dorsal 



Fig. 131. 



1-2. Ophiura rohusta. 3-4. 0. carnea. Part of oral and dorsal 

 side. X 6. (From Danmark's Fauna.) 



plates rather narrow , with outer edge strongly convex ; ventral 

 plates with a slight concavity in the outer edge, usually widely 

 separate and with a very obtuse proximal angle. Only one small 

 tentacle scale ; a few of the proximal pores may also have a 

 small scale at the outer edge. Three arm spines, placed at equal 

 distance from one another ; the uppermost one considerably 

 longer than the tw^o others, about as long as an arm -joint. Mouth 

 shields short and broad, scarcely reaching half-way to edge of disk. 

 Three to four small, simple mouth papillae on each side of jaw. 

 Colour in Ufe, bluish -grey or dark browaiish, often with white 

 spots, especially the radial shields usually whitish. Arms often 

 somewhat banded. It is a small form, scarcely reaching a size 

 of 10 mm. diameter of disk. Arms ca. three times the length of 

 the diameter of disk. 



Development unknown ; no reasonable suggestion can be 



