194 ECHINODERMS OF THE BRITISH ISLES 



at base of arm. Ventral plates with convex outer edge, fairly 

 close together, the proximal ones may even be contiguous. One 

 long, spine-like, thorny tentacle scale, which may be flattened. 

 Eight thorny arm spines, the upper ones more slender, about as 

 long as three arm segments. Three to four mouth papilla on each 

 side of jaw, not speciall}^ widened. Mouth shield rhombic or some- 

 what prolonged outwards. Colour not recorded. Arms ca. six times 

 the diameter of disk, which does not appear to surpass 9 mm. 



In British seas this species has been taken off S.W. Ireland in 

 ca. 1100-1280 m. (" Helga "). It is elsewhere known from the 

 Bay of Biscay, the Azores, and down to S. of the Canaries. 

 Bathymetrical distribution ca. 820-1740 m. 



This species is so near to 0. nodosa Lym. that it is rather 

 likely to prove identical therewith, in which case the name 

 nodosa, as the oldest, should be used for it. 



4. Ophiacantha ahyssicola G. O. Sars. (Fig. 105, 5, 6.) 

 (Syn. Ophiacantha millespina Verrill.) 



Disk closely covered with fine spinelets ending in some fine 

 thorns, giving a somewhat velvety appearance ; neither scales 

 nor radial shields distinct. Under side of disk without spinelets 

 in the proximal part, the scales being here distinct. Dorsal arm 

 plates of a very characteristic cup-shape, the side edges being 

 bent in the shape of an S. Ventral plates distinctly broader than 

 long, with straight outer edge ; both dorsal and ventral plates 

 widely separated. One small tentacle scale. Arm spines 6-8, 

 slender, delicate, finely thorny, the upper ones the longest, 

 equalling two arm joints in length. The spines may join in the 

 mid-dorsal line at the base of arms. The distal end of the arm 

 joints rather swollen. Three to four mouth papillae, the outer one 

 somewhat widened. Mouth shields almost cross-shaped, with a 

 groove in the outer lobe. Colour in life yellowish-brown, the oral 

 tentacles dark brownish-red, giving the living specimens a rather 

 characteristic appearance. Disk scarcely surpassing 7 mm. in 

 diameter, arms five to six times as long as the diameter of disk. 



In British seas this species has been taken in the Faroe 

 Channel (" Porcupine ") and off the W. Coast of Ireland 

 (" Helga ") in 520-990 m. It is elsewhere known from Lofoten 

 to Hardangerfjord on the Norwegian coast, from the Bay of 

 Biscay, the Azores, farther from Greenland and the east coast 

 of N. America. Bathymetrical distribution ca. 35-3500 m. 



