192 



ECHINODERMS OF THE BRITISH ISLES 



along the outer edge. Colour iu life yellowish- white. Reaches a 

 considerable size, ca. 15 mm. diameter of disk ; arms ca. 4-5 

 times that length. 



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



Fig, 105. — 1-2. Ophiacanthahidentata. 3-4. O.spectahilis. 5-6. O.ahyssi- 

 cola ; part of the oral side and arm segments from dorsal side. 7-9. 

 0. anomala. 7. Mouth shield. 8. Two dorsal arm plates. 9. Ventral 

 plate, with the tentacle scales. x 5. (From Danmark^s Fauna.) 



Channel (60° 11' N., 8° 15' W., 780 m., " Triton "). It is else- 

 where known from Lofoten and the Trondhjemfjord on the 

 Norwegian coast, from the Bay of Biscay, 800-1700 m. 

 (" Caudan "), and from the east coast of N. America. Bathy- 

 metrical distribution ca. 150-1700 m. 



2. Ophiacantha crassidens Verrill. (Fig. 106.) 



Disk with spines or crochets, which are slightly roughened 

 and bi- or trifid at the tip ; the scales of the disk distinct. 

 Radial shields may be distinct ; they are very small, widely 

 separated b}^ several rows of scales. Dorsal arm plates small, 

 triangular, well separated even at base of arm ; ventral plates wdth 

 convex outer edge, separated. One fairly large, oval tentacle scale. 

 Six or seven arm spines, the three lower flattened and bearing 

 several hooked spinules distally on their low^er edges, the upper 

 ones round, almost smooth ; the longest, the uppermost but one, 

 equals about 2 J arm segments in length. The mouth papillae 

 three on each side of jaw, large and flattened ; the papilla on 

 apex of jaw is the largest ; it is slightly furrowed longitudinally 

 and slightly overlapped by the other papillae. The mouth shield 

 is triangular, with the outer edge slightly concave (the shield 

 being thus heart-shaped) or convex. Colour in life not recorded, 



