NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 



93 



ANTHOPHIURA AXIOLOGA, new species." 



Disk 5 mm. in diameter; arms 12 mm. long. Disk rather high, 

 its vertical diameter at center being nearly 2 mm.; it is covered by 

 twenty-six plates, of which six are primary plates, ten are radial 

 shields, and ten are interradial plates, arranged in pairs, one plate 

 in each pair being marginal and one lying against two radial plates; 

 centrodorsal plate very high and very distinctly star-shaped. Radial 

 shields, longer than wide, closely joined, somewhat depressed below 

 the other disk plates. Arms cylindrical and slender, gradually taper- 

 ing to tip. First upper arm plate rather large, swollen, just beneath 

 outer ends of radial 

 shields; second plate 

 much smaller or want- 

 ing; no upper arm plates 

 beyond second joint. In- 

 terbrachial spaces below 

 covered by oral shield, a 

 supplementary plate, the 

 marginal plate so con- 

 spicuous from above, and 

 very wide genital plates. 

 The last carry no mar- 

 ginal papillae and hence 

 there is no trace of an 

 arm comb. Oral shields 

 somewhat triangular, 

 with outer corners 

 rounded, nearly as wide 

 as long. Adoral and oral 



plates moderately large, FIG. 32. ANTHOPHIURA AXIOLOGA. X10. a, FROM ABOVE; 6, 



about of a size. Oral FROM BELOW; c > SIDE VIEW OF THREE ARM JOINTS NEAR DISK ' 

 papillae small, close-set, about three on a side, of which outermost 

 is as wide as other two together. Basal under arm plates mod- 

 erately large, more or less pentagonal; first longer than wide, but 

 others wider than long; beyond the disk the plates are much 

 smaller and triangular, and after about the sixth joint are entirely 

 wanting. Side arm plates very large, meeting broadly above 

 and below; beyond the sixth joint they cover the entire surface of 

 the arm; each plate carries three sharp, rather thick arm spines, of 

 which the uppermost is longest and approximately equals half an 

 arm joint. Oral tentacle pore with two or three scales on each side 

 much as in Ophiura; it does not open into the mouth slit. Tentacle 



, signifying remarkable; the application is obvious, 



