220 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



actual contact with each other. Radial shields, or at least distal ends 

 of them, bare, roundish, well separated. Upper arm plates triangular, 

 those on basal half of arm more or less in contact and consequently 

 with proximal angle, more or less truncate, wider than long; distal 

 margin with a series of granules like those of the disk, and others are 

 often scattered on the surface of the plates. Interbrachial spaces 

 below less thickly granulated than disk. Genital slits very large. 

 Oral shield somewhat rhombic with lateral and distal angles rounded, 

 much wider than long. Adoral plates long, narrow, straight. Oral 

 papillae three or four on a side, and one at apex of jaw, long, flat, 

 pointed, subequal or apical one largest. First under arm plate small, 

 wider than long, narrower distally; second plate more or less triangu- 

 lar, wider than long; succeeding plates squarish, their outlines, par- 



FIG. 101. OPHIACANTHA CEWDISCA. x 5. a. FROM ABOVE; 6, FROM BEI.OW; c, SIDE VIEW OF THREE AKM 



JOINTS NEAR DISK. 



ticularly proximally, quite indistinct; they are well separated and 

 between each two there is more or less of a depression; it is difficult 

 to determine whether the side arm plates meet in the depression or 

 not. Side arm plates not very large, not meeting above and appar- 

 ently not below; each plate carries six short, stout, arm spines, of 

 which the upper two are longest, though hardly exceeding the joint, 

 and smoothest; lowest spines quite rough, at least near tip. Ten- 

 tacle scale single, not very large, pointed. Color (dried from alcohol), 

 yellowish or grayish. 



Localities. Albatross station 4957, off southern Japan, lat. 32 36' 

 N. ; long. 132 23' E., 437 fathoms, green-brown mud, fine gray sand, 

 foraminifera, bottom temperature 39.8, 1 specimen; station 4959, 



