NORTH PACTFIC OPTTIURANS IN NATIONAL MUSEUM — CLARK. 85 



Oral shields moderately largo, much longer than wide. Adoral 

 plates large, well defined, twice as long as wide; oral plates smaller, 

 more or less parallel, with a conspicuous unpaired plate at their 

 proximal ends. Oral papillse few and stout, about four on a side. 

 Genital slits small but genital scales large and conspicuous, especially 

 when seen from above; each scale carries a marginal series of about 

 eighteen short, thick, blunt papillae which change little in form as 

 they pass from lower to upper end of scale. Basal under arm plates 

 squarish, wdder than long, becoming octagonal, heptagonal, hex- 

 agonal, pentagonal, and at last rhombic ; they are broadly in contact 

 on basal half of arm but become widely separated distally. Side arm 

 plates not very large, w^ell separated from each other below and 

 above, except near tip of arm; each plate carries near its middle, on 

 distal margin, a single minute, papilla-like arm spine; there is no 

 trace of secondary arm spines. Oral tentacle pore opens into mouth 

 slit; it is protected by four or five flat, stout, scales on each side; 

 basal pores on arms similar, but with no scales on distal side of pore 

 after about the sixth joint; two tentacle scales continue to tip of 

 arm, on proximal side of pore. Color (dried from alcohol), buff, 

 grayish, or nearly white. 



Localities. — Albatross station 5036, off Hokkaido, Japan, lat. 41° 

 58' N.; long. 142° 30' 30" E., 464 fathoms, brown mud, bottom 

 temperature 37.9°, 5 specimens; station 5038, off Hokkaido, Japan, 

 lat. 42° 2' 40" N.; long. 142° 36' E., 175 fathoms, fine black sand, 

 broken shells, brown mud, bottom temperature 37.1°, 5 specimens; 

 station 5043, off Hokkaido, Japan, lat. 42° 10' 20" N.; long. 142° 

 15' 20" E., 309 to 330 fathoms, brown mud, fine black sand, coral, 

 sand, bottom temperature 37.9°, 11 specimens; station 5044, off 

 Hokkaido, Japan, lat. 42° 10' 40" N. ; long. 142° 14' E., 309 to 359 

 fathoms, gray sand, coral, sand, bottom temperature 32.1°, 6 speci- 

 mens. Bathymetrical range, 175 to 464 fathoms. Temperature 

 range, 37.9° to 32.1°. Twenty-seven specimens. 



Type.— Cat. No. 25528, U.S.N M., from station 5038. 



This is another species, very similar to sterea at first sight, but 

 easily distinguished by a glance at the arm spines. The arm comb 

 is also very different from those of sterea and stiphra. The conspicu- 

 ous unpaired plate at apex of the jaw is not characteristic as a similar 

 plate can usually be seen in sterea, ponderosa, and the other related 

 forms. 



OPHIURA ATACTA, new species." 



Disk 6 mm. in diameter; arms about 15 mm. long, probably. 

 Disk somewhat arched, covered with 150 to 175 scales, which are of 

 very diverse sizes and show no definite arrangement. Radial shields 



a yttaKToc, signifying out of order, in reference to. the disordered appearance of the 

 disk scales. 



