462 BULLETIN lOO^ UNITED STATES NATIONAL MUSEUM. 



Genus DIPLOPTERASTER Verrill. 



Diplopteraster Vekkill, Amer. Journ, Sci., vol. 20, 1880, p. 400. — Fisher, 

 1911, p. 370. Type, Pteraster multipes Sars. 



DIPLOPTERASTER MULTIPES PATAGIATUS Fisher. 



Plate 130, fig. 2. 

 Diplopteraster multipes patagiatus Fisher, 1916&, p. 28, 



Diagnosis. — Closely resembling D. multipes, but differing in hav- 

 ing narrower paxillar areas (exclusive of actinolateral membrane) 

 and in having the same number of spines in both sorts of furrow 

 combs (or if an unequal number, then one more in the nonprominent 

 combs instead of one less, as in multipes) ; adambulacral spines 

 longer. E=95 mm.; r=60 mm. (measured to edge of actinolateral 

 membrane) ; E=:1.5 r; r=50 mm., measured to edge of paxillar area; 

 breadth of paxillar area at interradius, 50 to 57 mm. In patagiatus 

 breadth of paxillar area at interradius=60 per cent or less of R; in 

 multipes it equals 80 per cent, or more, of R. 



Description. — The dorsal surface closely resembles that of mul- 

 tipes. The pseudopaxillae have pedicels slightly longer than the 

 2 central spines and decidedly longer than the 7 to 9 peripheral 

 spines. There are usually about 7 spiracular areas radiating from 

 the prominent central spines of a paxilla, with 6 to 9 spiracles to 

 each (thus fewer than in similar large examples of multipes; see 

 Fisher 1911(^, p. 371). The actinolateral membrane forms a fleshy 

 border to the entire ray, projecting beyond the paxillar area, so 

 that in life the contour of the specimen was probably nearly pen- 

 tagonal. Paxillar areas, broadly petaloid, convex, sharply differ- 

 entiated from the patagial membrane. 



Adambulacral spines slightly longer than in multipes. This is 

 very apparent upon comparison of specimens but is a little difficult 

 to describe. In multipes the longest spine of a comb equals the 

 length of 4 adambulacral plates, measured along the edge of fur- 

 row ; in patagiatus the longest spine equals 5 to 5.75 plates, in each 

 case starting with the adoral margin of the plate upon which the 

 spine has been measured, and omitting the fleshy flap of tissue at the 

 tip of spine. The number of spines along the ray, beginning with 

 the first plate, runs as follows, a star marking nonprominent plates: 

 6, 6*, 6, 6*, 6, 6*, 5, 5*, 6, 6*, 5, 6*, 5, 6*, 5, 5*, etc. In the nonprominent 

 combs the first or inner 2 spines are ordinarily short, the innermost 

 the shortest, while the next 4 are abruptly longer and subequal or 

 increasing slightly in length toward the outermost, which equals as 

 stated above, 5 to 5.75 adambulacral plates measured along edge of 

 furrow (rarely 6). When there are 6 spines to a prominent plate 



