NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 35 



OPHIOZONA POLYPLAX, new species." 



Disk, 17 mm. in diameter; arms 53 mm. long. Disk flattened, 

 covered with a close coat of three hundred (or more) scales, among 

 which the centro-dorsal and five radial can be easily distinguished, 

 though they are not conspicuous. Radial shields rather large and 

 widely separated. Upper arm plates more or less triangular, those 

 at base of arm becoming tetragonal by truncation of proximal angle; 

 first two or three much wider than long; only the basal four or five 

 in contact. Interbrachial spaces below covered with about thirty 

 plates. Oral shields pentagonal with sharp proximal angle and 

 rounded distal angles. Adoral plates large, wider without than 

 within, where they meet; oral plates small. Oral papillae about five 

 on each side, the penultimate largest. First under arm plate very 

 small, triangular or diamond shaped, much wider than long; second, 



C 



FIG. 8. OPHIOZONA POLYPLAX. x 3. a, FROM ABOVE; 6, FROM BELOW; c, SIDE VIEW OF TWO AND A 



HALF ARM JOINTS NEAR DISK. 



third, and fourth plates tetragonal, becoming hexagonal, longer than 

 wide; succeeding plates hexagonal with rounded distal angles, be- 

 coming pentagonal, wider than long, until outer part of arm is reached 

 where they are widely separated and are longer than wide> Side 

 arm plates large but little swollen, meeting above beyond the third 

 or fourth joint and below beyond the seventh or eighth; each plate 

 carries two thick, blunt spines of which the upper is the longer, 

 but is distinctly shorter than a joint. Tentacle scale single, moder- 

 ately large. Color (dried from alcohol) , nearly uniformly white, the 

 disk strongly tinged with gray above. 



Localities. Albatross station 4957, off southeastern Japan, 437 

 fathoms, green-brown mud, fine gray sand, foraminifera, bottom 

 temperature 39.8, 1 specimen; station 4969, off Shio Misaki Light> 

 Japan, lat. 33 23' 40" N. ; long. 135 33' E., 587 fathoms, brown mud, 



signifying many and nXa. signifying anything fiat and broad, a plate, in 

 reference to the numerous disk plates. 



