NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 145 



or less separated at least proximally. Upper arm plates tetragonal 

 or somewhat pentagonal, wider than long, becoming transversely 

 elliptical, more or less broadly in contact throughout. Interbrachial 

 spaces below naked. Oral shields longer than wide, somewhat 

 rounded diamond-shaped. Adoral plates large, roughly triangular 

 in outline. Oral papillae two on a side, one thick, rounded at apex 

 of jaw, and one long, thick and spine-like at outer corner of mouth 

 angle. Genital slits large. First under arm plate small, tetragonal, 

 narrowest distally; succeeding plates squarish with rounded corners, 

 about as wide as long, more or less completely in contact. Side arm 

 plates high but short, not meeting below or above, each with six or 

 seven flattened, blunt arm spines, of which the lowest is the longest 

 (but little exceeds a joint), while the uppermost is sometimes thick- 

 ened at tip. In a young specimen there are only four or five arm 

 spines. Tentacle scales two on each pore, large and of nearly equal 

 size. Color (dried from alcohol), disk, pale gray; interbrachial spaces 

 below, brown; arms yellowish or whitish. 



Localities. — Albatross station 3713, oft" Ose Zaki, Honshu Island, 

 Japan, 45 to 48 fathoms, volcanic sand, shells, rocks, 1 specimen; 

 station 3714, off Ose Zaki, Honshu Island, Japan, 48 to 60 fathoms, 

 volcanic sand, shells, rocks, 11 specimens. 



Tjfpe.— Cat. No. 25651, U.S.N.M., from station 3714. 



Although the specimen from station 3713 is less than 4 mm. across 

 the disk and has only four or five arm spines, there is no doubt what- 

 ever of its identity with the large ones. The naked interbrachial 

 spaces, spine-like oral papillae, long oral shields, large tentacle scales, 

 and characteristic arm plates are unmistakable distinguishing marks. 

 Combined with the numerous arm spines of the adult they make the 

 species an easily recognized one. 



AMPHIURA ACRYSTATA, new species.o 



Disk 10 mm. in diameter; arms about 130 to 150 mm. Disk usu- 

 ally more or less naked at center and in the interradii, but around 

 the radial shields there is a variable amount of close, fine scaling; 

 in some specimens (fig. 58^) the entire disk is covered by minute scales. 

 Radial shields long and narrow, in contact distally. Basal upper arm 

 plates rather small, somewhat pentagonal, with a short proxinial side; 

 succeeding plates more transverse, elliptical (though sometimes angu- 

 lar), very much wider than long, in contact throughout. Inter- 

 brachial spaces below naked, or more or less covered with minute 

 scales. Oral shields nearly oval, almost as wide as long. Adoral 

 plates large, narrow and meeting within (or nearly so), very broad at 



a 'AKpumaroc, signifying surrounded ivith nets, in reference to the appearance of the 

 radial shields. 



34916°— Bull. 75—11 10 



