NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK 69 



OPHIURA CRYPTOLEPIS, new species.a 



Disk 20 mm. in diameter; arms about 55 mm. long. Disk com- 

 pletely covered by a thick granular skin, through which, in adults, 

 not even radial shields can be seen ; in many smaller specimens out- 

 lines of radial shields and even of disk scales can be more or less easily 

 distinguished. Upper arm plates small, tetragonal, all but first one 

 or two much longer than wide, with a narrow, proximal, and a strongly 

 convex, distal margin; on basal third or half of arm they are in con- 

 tact with each other, but distally they become triangular and separate. 

 Interbrachial spaces below like disk above. Oral shields and all 

 mouth parts, under arm plates, tentacle pores, and tentacle scales, 

 essentially as in calyptolepis, the differences being trivial and of no 

 systematic importance; tentacle pores extend out six joints on arm, 

 and first under arm plate is relatively smaller. Arm comb well 

 developed, forming a conspicuous marginal fringe just distal to radial 



FIG. 19. OPHIURA CRYPTOLEPIS. X2.5. a, FROM ABOVE; b, FROM BELOW; c, SIDE VIEW OF TWO ARM 



JOINTS NEAR DISK. 



shields; the two parts do not unite into a single comb. Side arm 

 plates large, meeting below but not above at base of arm ; each plate 

 carries seven to nine arm spines, lowest very distinctly largest and 

 may equal or exceed half a joint; in some cases, especially small 

 specimens, it appears to be next to lowest spine, which is longest, but 

 in fact, what looks like lowest spine is tentacle scale. Color (dried 

 from alcohol) , yellow, yellowish, cream color or nearly white ; some of 

 the young specimens are dull purplish gray. 



Localities. Albatross station 2858, off Alaska, lat. 58 17' N.; 

 long. 148 36' W., 230 fathoms, blue mud, gravel, bottom tempera- 

 ture 39.8, 1 specimen; station 3070, off Washington, lat. 47 29' 30" 

 N.; long. 125 43' W., 636 fathoms, green mud, bottom temperature 

 37.9, 2 specimens; station 3332, Bering Sea, lat. 54 2' 50" N.; long. 

 166 45' W., 406 fathoms, rocky, sand, bottom temperature 37.8?, 

 1 specimen; station 3337, off Alaskan peninsula, lat. 53 55' 30" N.; 

 long. 163 26' W., 280 fathoms, green mud, bottom temperature 



e, signifying hidden, and Xmk , signifying scale, in reference to the com- 

 pletely concealed disk scales. 



