298 



BULLETIN 7G, UNITED STATES NATIONAL MUSEUM. 



Parallel with the adanibulacrals arc two series of marginal plates, each of which 

 bears a group or comb of two to four conspicuous spinclets. A short series of actinal 

 intermediate plates is wedged between the inferomarginals and adambulacrala 

 proximali}', and similarly a few intermarginal plates, bearing one or two spinelets, 

 occur between the two series of marginals proximally. In some specimens the 

 marginal plates are regular, in others irregular and difficult to follow. 



The adambulacral spinelets are typically in a single transverse comb of three to 

 five on the actinal surface, the inner being the longest and much longer than width of 

 plate; the spinelet within the furrow is much shorter and slenderer than the longest 

 of the above — about one-third its length. 



Madreporic body small and inconspicuous, with a few coarse striations, and 

 several spinelets on its surface. 



Variations. — Two much larger specimens (R=4S mm.) from station 4772, 344 

 to 372 fathoms, Bowers Bank, Bering Sea, have been referred with some hesitation 

 to this species. As compared with aspera the rays are much weaker, the skeletal 

 elements slenderer, the papular areas larger, and not nearly so sunken, the spinelets 

 more dehcate, longer, and sharper, and the adambulacral spines longer and slenderer. 

 These specimens differ from those described above in having a series of mtermarginal 

 plates nearly to tip of ray, an 1 at the base two or three series. The actinal interme- 

 diate series is very variable in length, but docs not extend to end of ray. The mar- 

 ginal plates are inconspicuous an.I bear only two or three spinelets. 



Type.—C&i. No. 27782, U.S.N.M. 



Type-locality. — Station 4423, between Santa Barbara and San Nicholas Islands, 

 CaUfornia, 339 to 216 fathoms, green sand shells. 



Distribution. — Vicinity of Santa Barbara Island, CaUfornia; Shumagin Islands, 

 Bering Sea (Bowers Bank and off Kamchatka), 178 to 682 fathoms. The northern 

 form differs more or less from the type. 



Specimens examined. — Thirty-eight. 



Specimens of Henrida asthenactis examined. 



