NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 269 



Tli contrast between the disk and the interbrachial spaces below, 

 both in texture of skin and in color, is most striking, and the very 

 long arms with nearly smooth arm spines are additional features of 

 interest. The specimens before me range in disk diameter from 4.5 

 to 11 mm. 



FAMILY OPHIOMYXIM;. 



OPHIOBYRSA ACANTHINOBRACHIA, new species, a 



Disk 20 mm. in diameter; arms about 280 mm. long. Disk covered 

 by a soft skin, which carries numerous scattered plates, each of which 

 bears a single, small spinelet. Radial shields faintly indicated and 

 part of distal end more or less visible. Upper arm plates broken up 

 into small fragments, each one of which carries a little spinelet like 

 those of disk; these transverse spine-bearing bands are separated 

 from each other by bare skin. Interbrachial spaces below like "disk. 

 Genital slits rather big. Mouth parts and lower surface of arms more 



FIG. 134. OPHIOBYR.SA ACANTHINOBRACHIA. X 2.5. a, FROM ABOVE; b, FKOM BELOW; c, SIDE VIEW OF 



TWO AKM JOINTS NEAR DIRK. 



or less concealed by skin. Oral shields rounded triangular about as 

 long as wide. Adoral plates large, short, and wide, hardly meeting 

 within; oral plates about as large. Oral papilla? few, minute, irregu- 

 lar. Teeth (or tooth papillae) spiniform, rough at tip, in two more 

 or less irregular vertical series. Under arm plates obscure, squarish, 

 with rounded corners, wider than long, distal margin with a deep 

 notch. Side arm plates small, each one bearing six or seven small, 

 acute, subequal skin-covered arm spines, about half as long as joint; 

 lowest arm spine hooked. No tentacle scales. Color (dried from 

 alcohol), dull yellowish or reddish brown; young specimens, yellow. 



Localities. Albatross station 4894, Eastern Sea, lat. 32 33' N.; 

 long. 128 32' 10" E., 95 fathoms, green sand, broken shells, pebbles, 



a 'Aic&vdivof, signifying thorny, and ftpa%'twv, signifying arm, in reference to the numer- 

 ous small spines on the upper arm plates, 



