34 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM, 



OPHIOZONA PLATYDISCA, new species.o 



Disk 12 mm. in diameter; arms about 40 mm. long. Disk very 

 flat and thin, covered by about two hundred scales among wliich the 

 centro-dorsal, the five primary radial, and the radial shields are 

 conspicuous, while other large plates occur between the proximal 

 ends of the radial sliields and in the interradii; but there is no con- 

 spicuous marginal plate in each interradius. The upper arm plates, 

 the covering of the jaws, the oral sliields, the oral papillae, the under 

 arm plates, the side arm plates and arm spines, and the tentacle 

 scales are like those of elevata. Interbrachial spaces below covered 

 with about thirty plates, no one of which is conspicuoush^ larger than 

 the others. Color (dried from alcohol) , dull, light purple, variegated, 



Fig. 7.— Ophioeona platydisca. x4. a, from above; 6, from helow; c, side view ok three arm 



JOINTS NEAR DISK. 



with whitish; arms with four narrow, irregular, whitish cross-bands; 

 lower surface of disk and arms, whitish. 



Locality. — Albatross station 4965, off Hiro Misaki Light, Japan, 

 lat. 33° 35' 20" N.; long. 135° 10' 50" E., 191 fathoms, dark green- 

 gray sand, shells, bottom temperature 49.4°, 3 specimens. 



Type.—C&t. No. 25717, U.S.N.M., from station 4965. 



It seems quite possible that this is the adult form of elevata, but 

 the differences in the form and scaling of the disk have induced me 

 to keep them separate for the present. The absence of a large 

 marginal plate in each interradius, above and below, distinguishes 

 platydisca, but this may be the result of its considerably larger size. 

 From hispinosa tliis species is at once distinguished by its upper 

 arm plates and shorter arm spines. 



aflXaruc signifying flat, and dioKoc signifying dish, in reference to the flat, thin, 

 disk. 



