NORTH PACIFIC " OPHIURANS IN NATIONAL MUSEUM CLARK. 



181 



OPHIOMITRA DISCYCLA, new species, 't 



Disk 5.5 mm. in (liainoter; aims about .'52 mm. lontj;. Disk circular, 

 covered by numerous (125 to 175) plates of irregular size, one on each 

 interradial margin being decidedly larger than the rest. Radial 

 shields short and wide, closely joined except at their proximal end. 

 Upper arm plates small, diamond-shaped or triangular with convex 

 distal margin, about as wide as long, widely separated from each 

 other. Interbrachial spaces below covered by very few, rather large 

 plates. Genital slits short. Oral shields diamond-shaped, much 



Fig. 82.— Ophiomitra discycla. X 9- o, from above; b. from below; c, ripe view of two arm 



JOINTS NEAR DISK. 



wider than long. Adoral plates very large, about as broad without 

 as within where they meet; oral plates small and indistinct. Oral 

 papillae three on a side and one at apex of jaw; outermost, broad, 

 flat and truncate, apical one, broad but sharp, others, narrow and 

 pointed. First under arm plate large, somewhat hexagonal, mder 

 within than distally; succeeding plates very much wider than long, 



« J/f, signifying double, and kukXoc, signifying ring, in reference to the two nearly 

 complete rings, formed by the arm spines of the two basal joints. 



