NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 



51 



herewith reveal some of these notable variations; figs. Hd-f are 

 from a specimen having the disk 7 mm. in diameter, while figs. 

 lla-c are from a much larger specimen, with a disk 11 mm. across. 

 A number of the specimens are labeled " OpJiioglypTia robusta (Ayres) ," 

 but this is clearly an error. I have not yet seen a specimen of 

 robusta from Bering Sea or the North Pacific. It is rather remark- 

 able that neither Grieg nor Meissner 6 mention this species, although 

 both writers in their bibliographies refer to Ludwig's paper. 



OPHIURA LEPTOCTENIA, new species.c 



Disk 11 mm. in diameter; arms about 30 mm. long. Disk flat and 

 more or less circular, covered by a close coat of two or three hun- 

 dred scales, among which 

 the centrodorsal is easily 

 distinguishable, though it 

 is seldom so large as in fig. 

 12a; one radial plate just 

 proximal to or between 

 radial shields is commonly 

 larger than the other disk 

 scales. Radial shields large, 

 longer than wide, some- 

 times wholly separated, but 

 usually in contact distally, 

 inner sides nearly or quite 

 straight, but more or less 

 strongly diverging. Basal 

 upper arm plates tetrago- 

 nal, with edges more or less 

 curved, much wider than 

 long; near middle of arm 



they are about as long as FIG. 12. OPHIURA LEPTOCTENIA. X5. <Z,FROM AHOVK; 



wide, and at tip they are 



very much longer than wide and are nearly triangular; in contact 

 with each other whole length of arm. Interbrachial spaces below 

 closely covered with numerous small scales. Oral shields much 

 longer than wide, with a broad proximal angle and a curved distal 

 margin. Adoral plates and oral plates well marked and about of 

 a size. Oral papilla? numerous, six or more on a side, narrow 

 and sharp. Teeth narrow and pointed. Genital slits conspicuous, 

 reaching from oral shield to margin of disk. Genital scales large, 



Fauna Arctica, vol. 1, pt. 2, 1900, pp. 259-286. 

 b Bronn's Thierreichs, vul. 2, pt. :?, 1901, p. 925. 



c AeitTOf, signifying fine, slender, and ursviov, signifying a small comb, in reference 1o 

 the slender comb papillae . 



