NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 227 



upper arm plates, the arm spines, and the oral papillae, its characters 

 are so unique I have no hesitation in making it the type of a new 

 species. I would call particular attention to the huge, spiniform 

 oral papillae; the very large first under arm plate widely separated 

 from second; the absence of tentacle scales, and the very charac- 

 teristic lower arm spines. 



OPHIACANTHA HYLACANTHA, new species.a 



Disk 11 mm. in diameter; arms about 60 mm. long. Disk covered 

 by numerous stout, pointed, rough spines, nearly or quite a milli- 



FIG. 106. OPHIACANTHA HYLACANTHA. x 4.5. a, FROM ABOVE; 6, FKOM BELOW; c, SIDE VIEW OF TWO 



ARM JOINTS NEAR DISK. 



meter long. Among the spines are scattered coarse granules, but 

 whereas the spines are chiefly near the center of the disk, the gran- 

 ules are chiefly marginal, particularly distal to the radial shields. 

 Radial shields large, well separated, rather longer than wide, bare 

 and smooth. Upper arm plates more or less triangular, as long as 

 wide or longer; basal ones in contact, but farther out they are sep- 

 arated; some basal ones bear marginal granules, as in normani. 



a "TXi], signifying forest, and amvda, signifying spine, in reference to the forest of 

 spines on the disk. 



