NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 241 



within. Oral plates small antl so nearly parallel with adorals that 

 the jaw is somewhat rounded and projects very little. Oral papillae 

 four on a side and usually an infradental one at apex of jaw; the 

 papillas are thick and blunt, and the outermost is clearly the largest. 

 First under arm plate very large, somewhat rounded, hexagonal, wider 

 than long; second plate somewhat larger, pentagonal, widest distally; 

 succeeding plates more rounded, soon becoming elliptical and then 

 onger than broad, and ultimately long pentagonal with distal end 

 rounded; all the under arm plates are more or less separated from 



Fig. 115. — Ophiolebes brachygnatha. X 5. a, from above; 6, from below; c,side view of three 



ARM joints near DISK. 



each other except the first two. Side arm plates moderate, not meet- 

 ing above and only slightly so below; each plate carries seven or eight 

 stout, blunt arm spines; upper two longest, exceeding joint, smooth; 

 next two similar, but distinctly smaller; lowest three or four very 

 much smaller, somewhat flattened, and with rough tips; they lie more 

 or less appressed to lower surface of arm, pointing distally and in- 

 ward. Tentacle pores small, first pair with a more or less prominent 

 spiniform tentacle scale; a few other pores may have minute tentacle 

 scales, but as a rule the scales are completely replaced functionally by 

 the lowest arm spines. Color (dried from alcohol), light yellowish. 

 34916°— Bull. 75—11—16 



