376 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



of the paxillar spines; therefore quite different from hoMeri. There are seven 

 irregular longitudinal rows of these points, while in koehleri (as in nobilis) there 

 arc six regular series, a median radial being wanting. In violaceus the furrow 

 spinelet (without the membrane) is as long or a trifle longer than the segmental 

 papilla, while in kmhleri the latter is one and one-half times as long as the furrow 

 spinelet. 



Hymenaster nobilis was taken at (Jhallenger station 158, south of Austraha, 

 1,099 miles southwest of Cape Otway, 1,800 fathoms globigerina ooze, and by the 

 Investigator in the Bay of Bengal, 1,748 fathoms. It is of interest to find such a 

 closely related form in the extreme north Pacific. 



I take pleasure in dedicating this handsome species to Dr. R. Kcehler, of the 

 University of Lyon. 



HYMENASTER PERISSONOTUS Fisher. 

 PI. 109, figs. 1, 2; pi. 115, figs. 1, la-e; pi. 117, figs. 3, 3a. 

 Hymenaster perissonotus Fisher, Ann. and Mag. Nat. Hist., ser. 8, vol. 5, Feb., 1910, p. 170. 



Diagnosis. — General form depressed, nearly pentagonal, with subplane abac- 

 tinal surface and extensive interradial webs supported by actinolateral spines, 

 which are conspicuously heavier beyond middle of ray. Paxillar area not con- 

 spicuously raised. Marginal paxillae conspiciiously larger than the three 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 fibers, which radiate from tips of delicate paxilla spinelets, usually 

 three or four of these to a paxilla; points of spinelets uniformly spaced on supra- 

 dorsal membrane, and individual paxillffi not distinguishable. Adambulacral 

 spinelets two, or less often three; oral spines five or six, rarely seven, suboral 

 spines one or two; aperture papillse large, ovate. 



Description. — General form pentagonal and very flat, the sides of the pentagon 

 being nearly straight, except that the tips of the raj's are shghtly prolonged; R = 70 

 mm.,r = 50mm.,R=l. 4r. Lateral web extending beyond paxillse and supported by 

 the stout actinolateral spines. There is only a very narrow interradial strip free from 

 the spines, of which those near middle of ray are conspicuously stouter than the 

 proximal ones. Supradorsal membrane thin, and when the epidermis is rubbed (as 

 it usually is), very translucent, showing thread-like slender muscle bands running 

 between the tips of the paxillar spines. These fibers are not of iiniform thickness. 

 They crisscross in every direction and branch, and are more numerous in some 

 specimens than in others. Paxillar areas broadly petaloid, but not raised, the 

 abactinal surface being as near flat as possible. Adjacent areas are confluent 

 along the adcentral half of r. Paxillar spines forming rather abrupt low imiformly 

 spaced protuberances over the paxillar area, individual paxillie being not at all 

 discernible. Spiracula large for this genus, larger and fewer than in quadrispv- 

 nosus, and scattered without order. The larger specimens have more than the 

 smaller. A few occur on the interradial area outside the paxillar region on finger- 

 like outpouchings of the nidamental cavity. 



