NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 157 



the presence of four arm spines on the basal joints of tlie arm arc 

 excellent diagnostic characters. 



AMPHIODIA MACRASPIS, new species." 



Disk 11 mm. in diameter; arms about 150 mm. long, probably. 

 Disk rather soft, inclined to be swollen and more or less deeply 

 notched in interradii, covered with very numerous scales, which are 

 much larger around the radial shields than they are at center of disk 

 and in the interradii. Radial shields long and curved, rather more 

 than tlu'ee times as long as wide, separated throughout or in contact 

 distally. Upper arm plates more or less triangular, with truncated 

 angles, in contact with each other, at least at base of arm, rather 

 wider than long. Interbrachial spaces below covered by a close, fine 

 scaling. Oral shields pentagonal or more hexagonal, with somewhat 

 rounded angles, much wider than long. Adoral plates large, about 

 twice as long as broad, nearly or quite meeting withm. Oral papillae 

 three on a side (in large specimens there is an additional small 



Fig. (iC— Amphiodia macraspis. X 5. a, from above; 6, from below; c, side view of three arm 



JOINTS near disk. 



papilla at the distal end of the moutli slit), subequal, though the one 

 at apex of jaw is rather thicker than the others; between first and 

 second, the tentacle scale of the first oral pore appears and might be 

 mistaken for another papilla. Genital slits, large. First under arm 

 plate very small, wider than long; succeeding plates tetragonal, 

 nearly square but sometimes longer than wide (as in type, fig. 66, b), 

 and sometimes wider than long; broadly in contact throughout. 

 Side arm plates small, not quite meeting above at base of arm, widely 

 separated below; each plate carries five (at base of arm, sometimes, 

 six) slender, sharp spines, of which the lowest is the longest, nearly 

 equalmg the joint, but the uppermost is not the shortest. Tentacle 

 scale suigle, small ; on some of the basal pores, a second scale is present. 

 Color (dried from alcohol), disk, gray; arms, dirty whitish; in several 

 specimens the radial shields, some of the larger disk scales, and the 



aMaKpSc, signifying long, and daTzcc signifying shield, in reference to the long, 

 narrow radial shields. 



