230 BULLETIN "76, UNITED STATES NATIONAL MUSEUM. 



HIPPASTERIA LEIOPELTA ARMATA, new subspecies 

 PI. 121, fig. 2; pi. 122, figs. 1, 2. 



Diagnosis. — Intermeiliatc in <jeneral appearance between leiopelta and pTirygiana 

 but nearer the former; differing from leiopelta in having one, and sometimes in the 

 interbrac'hial arcs two, stout rigid conit'al spmes to each marginal plate, and in 

 having much more numerous, and higher, abactinal pedicellarise; actinal pedicellariae 

 shorter and liigher; adarabulacral spines longer, the single furrow spine tapering 

 and blunt, not davate, as in leiopelta. R=73 mm.; r=42 mm.; R=1.7 + r. 



Description. — Abactinal plates bear more numerous pedicellariaj than typical 

 leiopelta, and the jaws are relatively higher in proportion to the length, about as in 

 spiiiosa and higher than in phrijgiana. The median radial plates bear a low thimble- 

 shaped tubercle, scarcely higher and often lower than width of plate. Many of 

 the other abactinal plates bear one or two central granules wliich may become 

 enlarged into a low tubercle, never conspicuous. In leiopelta such tubercles occur 

 only rarely or are entirely absent, the surface of the plate being smooth. A single 

 series of smooth granules surrounds each ])late. Pajnils', as in leiopelta, all over 

 abactinal surface except a narrow interradial line. 



Marginal plates more tumid than iia leiopelta. On the lateral face on a raised 

 boss is a stout conical rigid spine, and sometimes in the interbrachial arc a second 

 occurs in a transverse line. However, most of the abactinal surface of the super- 

 omarginals and the corresponding face of the inferomarginal is bare. Scattered 

 bivalved pedicellariae smaller than those of abactinal plates also occur in the inter- 

 brachial arc. These are not present in leiopelta. 



The actinal pedicellariae are shorter and higher than in leiopelta, as well as 

 much more numerous. In leiopelta the pedicellariae liave the appearance of being 

 immersed in the granulation, while in armata they stand well above it (as in spiiiosa). 

 The adambulacral spines (one furrow and one actinal) are longer and relatively 

 slenderer than in leiopelta and taper slightly to a very blunt tip. In leiopelta they 

 are tliick and often clavate. The actinal spine is the shorter. Occasionally an 

 adoral spinelet is present on the furrow series, or merely a granule. Irregular 

 granules cover the remainder of the plate. 



Type.— Cut. No. 27887, U.S.N.M. 



Type-locality. — Albatross station 4804, off Simushir, Kuril Islands, 229 fathoms, 

 coarse pebbles, black sand. 



Distrihution. — Known only from the type-locality. 



Specimens examined. — Five; from the type-locahty, three; from station 4803, 

 same locality, depth, and bottom, two. {Albatross, 1906.) 



RemarJcs. — A small specimen with R 32 mm. and hence about the same size 

 as the type of leiopelta has the characters of the race as well markeil as the type, with 

 the exception of the marginal pedicellariae. This shows that armata is not simply 

 a iu[\x grown leiopelta. (PI. 122, fig. 1.) 



Armata tliffers from kurilensis in lacking the conspicuous abactinal spines and 

 pointed granules, as well as in the armature of the adambulacrals. It differs from 

 ty[)ical pTirygiana in being more pentagonal in shape, with notably shorter rays, 

 in having only one furrow spine, higher pedicellari^, and more massive marginals 



