500 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



On the first four to six adambulacral plate;^ tliere is a pair of 

 spines of about the same size, one proximal and one distal, next the 

 furrow. At right angles to these, and to the furrow, are at first 

 two, then three, slightly smaller spines forming a comb. Beyond the 

 fourth to sixth adambulacral plate the distal spine of the pair next 

 the furrow moves downward and inward toward the furrow to a 

 position in line with the other spines, so that a comb of five echinate 

 spines is formed of which the innermost, at the edge of the am- 

 bulacra] groove, is slightly longer and stouter than the others, and 

 the outermost is slenderer. 



The mouth plates are large and triangular. The outer ends, ad- 

 joining the adambulacrals, make an angle of about 45° with their 

 inner opposed borders, and the length is about three times the great- 

 est width. The pair of mouth plates dips downward toward the 

 mouth, the inner surface rising toward the tip and toward the outer 

 borders. Each plate bears on its long outer side four cylindrical 

 spines resembling those on the adjacent adanibulacrals. with a larger 

 and more tapered spine at the inner angle and a smaller one on the 

 inner portion of the distal border. 



The tube feet are in two rows. 



Localities. — Attu, Aleutian Islands; 2-7 fathoms; sandy bottom; 

 Victor B. Scheffer, June 10, 1937 (type. U.S.N.M. no. E. 5600; origi- 

 nal no. 44). (PI. 57, figs. 1, 2.) ' 



Amchitka, Aleutian Islands, 1-5 fathoms; Victor B. Scheffer, July 

 19, 1937 (1, U.S.N.M. no. E. 5601; original no. 9). (PI. 57. figs. 3, 4.) 



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