170 New Pterasteridse from the North Pacific. 



bb. Median radial paxillse not greatly reduced 

 in size, with 4 basal lobes ; 9 rows of 



paxillae along ray ; very numerous small [Fisher, 



spiracula ; adambulacral spinelets 4 or 5 . quadrispinosus, 



Hymenaster koehleri, sp. n. 



Very near to H. nobilis, Wyville Thomson, which it re- 

 sembles in general appearance, number and arrangement of 

 paxillar spines and adambulacral spines, but from which it 

 differs in the following details: — spiracula in very definite 

 circumscribed areas, not confluent between the paxillar 

 crowns ; the regular transverse spiracular areas o£ inter- 

 brachial web of nobilis absent or only indicated irregularly 

 toward ends of rays; replaced proximally by detached 

 scattered small spiracular areas; furrow spinelet much 

 shorter than segmental papilla ; oral spines short (half 

 length of interradial suture, or less). R=100 mm., 

 r=70 mm., R=l-4 r. 



Bering Sea, south of Pribilof Islands, 1771 fathoms. 

 Bottom, blue ooze. 



Named after Dr. R. Koehler. 



Hymenaster per issonotus, sp. n. 



General form depressed, nearly pentagonal, with subplane 

 abactinal surface and extensive interradial \vel>3 supported 

 by actinolateral spines, which are conspicuously heavier 

 beyond middle of ray. Paxillar area not conspicuously 

 raised. Marginal paxillse conspicuously larger than the 3 

 series of abactinal, the radial being very short and, distally, 

 rudimentary. Supradorsal membrane close to abactinal wall 

 along median radial area. Spiracula large, scattered, fairly, 

 but not very, numerous ; membrane with very numerous 

 criss-crossing muscle-fibres, which radiate from tips of delicate 

 paxilla spinelets; usually 3 or 4 of these to a paxilla ; points 

 of spinelets uniformly spaced on supradorsal membrane, 

 and individual paxillse not distinguishable. Adambulacral 

 spinelets 2 or less often 3 ; oral spines 5 or 6, rarely 7, 

 superoral spines 1 or 2 ; aperature papillae large, ovate. 

 R = 70 mm., r=50 mm., R=T4 r. 



Off San Diego, California, 984 fathoms. Bottom, grey 

 mud. Ranges to Bering Sea. 



