NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM — CLARK. 31 



an infradental papilla commonly present. Teeth about five, very 

 broad, flat, and rounded. First under arm plate more or less trian- 

 gular, much smaller than second ; second and succeeding plates quad- 

 rilateral, wider than long, broadly in contact. Side arm plates small, 

 low, each with three short, thick, blunt arm spines, of which the 

 middle one about equals the arm joint; the uppermost is decidedly 

 shorter, the lowest decidedly longer. Tentacle scales, two on prox- 

 imal side of pore, and two, or often only one, smaller, on distal side. 

 Color (dried from alcohol), deep olive-gray; arms irregularly banded 

 with light and dark olive-gray. 



Localities. — Japan, five specimens; Misaki, Japan, nine specimens; 

 Enoshima, Japan, one specimen; Ayukawa, Japan, six specimens. 



Type.— C^i. No. 25621, U.S.N.M., from Misaki, Japan. 



Fig. 5.— Ophioplocus japonicus. X3. a, from above; 6, from below, c, side view of three arm 



JOINTS near disk. 



Although this species is superficially much like imhricatus, it can 

 be at once distinguished from that species by the genital slits which 

 in imhricatus are very short, and never start at the oral shield. In 

 this particular japonicus resembles the species from Southern Cali- 

 fornia (esmarJci), but it is at once distinguished from that species by 

 the arm spines, which in esmarM are short and nearly equal. Lyman 

 long ago "■ pointed out the peculiar genital slits of Japanese speci- 

 mens of Ophioplocus. 



OPHIOZONA ELEVATA, new species.!' 



Disk 9 mm. in diameter; arms about 27 mm. long. Disk elevated, 

 2 mm. thick, covered with about 100 to 150 flat plates or scales, 

 among which the most conspicuous are the centrodorsal, two radial 

 in each radius, one of which lies between the ends of a pair of large 



a Bull. Mus. Comp. Zool., vol. 3, 1874, p. 228. 



bElevatus, signifying raised up, in reference to the elevated disk. 



