210 BULLETIN 16, UNITED STATES NATIONAL MUSEUM. 



Specimeiis examined. — Seventy-three, from the following locahties: 

 Specimens of Ceramaster japonicus examined. 



3221.. 

 3330.. 

 3331.. 

 3346.. 



34gS.. 

 3489.. 

 3502.. 

 3G0S.. 

 4768.. 

 4774.. 



Bering Sea, norlb of Unalaska . 



Off Tillamook Bay, Oregon 



West of Pribilof Islands, Bering Sea.. 



.do. 



Bering Sea, south of St. George Island 



Bering Sea between St. George and Unalaska.. 

 Bowers Bank, Bering Sea, 64° 12' N.; I79°07' E. 

 Bowers Bank, Bering Sea, 54° 33' N.; 178° 45' E. 



.do. 



MIsaki, Japan.. 



Depth. 



Nature of bottom. 



green mud 



black sand, mud 



mud 



green mud 



green mud, gray sand 



do 



green mud, dark sand 



gray sand 



green mud , 



green mud, black speck, 



foraminifera. 

 do 



V. S. Nat. Mus. 



Do. 



Stanford. 



Remarks. — In lieu of giving a detailed description of tliis species, I have hsted 

 the chief variations presented by a large series of specimens. The various figures 

 will serve sufficiently, in connection with Sladen's excellent description of the type- 

 specimen, for purposes of identification. Except in the case of young specimens 

 there is no danger of confusing this species with C. granularis, to wliich it seems 

 to be rather closely related. The salient differences have been already pointed out. 

 The differences between japonicus and leptoceramus are mentioned below under the 

 latter species. 



CERAMASTER LEPTOCERAMUS (Fisher). 

 PL 39, figs. 1-3; pi. 58, figs. 3, 3a; pi. 60, fig. 2. 

 Tosia Icptocerama Fisher, Bull. Bur. Fisheries for 1904, vol. 24, June 10, 1905, p. 806. 



Diagnosis. — Related to C. japonicus Sladen, but with secondary abactinal 

 plates, thinner disk and margin, spaced bead-like actinal granules, and shorter and 

 more numerous furrow spinelets. Type, R = 63 mm.; r = 44 mm.; R = 1.43 r. 

 Disk thin, general form pentagonal, marginal plates small, closely granular, some- 

 times with a bare spot ; superomarginals not in contact distally ; radial areas inflated ; 

 body very thin interradially (about 1.5 mm.). Abactinal plates stellate on papular 

 areas, raised into spaced tabula bearing numerous granules and usually also a small 

 two-jawed pediceUaria ; numerous smaller secondary plates intercalated between the 

 larger ones on proximal part of papular areas. Actinal intermediate plates with 

 spaced bead-like granules and two-jawed pediceUariae. Adambulacral plates with 

 a regular furrow comb of seven or eight short compressed quadrate slender spine- 

 lets, and two rows of actinal granules. 



Description. — Abactinal surface covered with spaced, low, tabulate plates, 

 arranged with great regularity in a radial series, wliich is largest, and numerous 

 other parallel series, decreasing rapidly in size toward the margin, where the plates 

 are small and more crowded. In center of disk the plates are arranged without 

 order, and are more or less irregular in a narrow interradial area, which is free from 

 papula-. Bases of plates of radial areas, when viewed from the iimer side, in a 

 prepared specimen are substellate, regularly with si.x truncate or blunt ]irocpsses, 



