366 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



long. 121° 11' 00" E.) ; 905 meters (495 fathoms) ; March 31, 1909; 

 gy. M., co. S. 



One specimen (Cat. No. 41075, U.S.N.M.). 



Description. — The specimen from station 5274 is the larger, and 

 the diameter of its disk reaches 9 mm.; in the other this diameter 

 does not exceed 6 mm. The arms are incomplete; the longest are 

 preserved over a length of from 12 mm. to 14 mm., and they scarcely 

 could have much exceeded this length. 



These two specimens show a slightly different arrangement of the 

 plates of the dorsal surface of the disk, which appears solely due 

 to a difference in age. I shall consider them individually, designat- 

 ing the one from station 5245 by the letter A and that from station 

 5274 by the letter B. 



The disk is pentagonal, thick, with both the dorsal and the ventral 

 surfaces a little convex. In A, in which the plates of the dorsal sur- 

 face of the disk are less numerous than in the other, they are very large, 

 and in the very narrow intervals which they leave between them 

 there are intercalated a few small plates. The plates of the primary 

 rosette are very large, and they cover almost half of the surface of 

 the disk. The dorso-central is pentagonal and in contact for the 

 whole extent of its margin with the primary radials, which are 

 quadrangular, with a strongly convex distal border, and a little 

 broader than long. These five radial plates are also in contact with 

 each other. In the interradial spaces there are three large successive 

 plates, the first rounded, and the second quadrangular and almost 

 as long as broad ; the third, which is also quadrangular, is found at 

 the periphery of the disk of which it delimits the vertical face, and 

 only its very narrow border is visible when the animal is viewed from 

 above. In the radial spaces there is found only a small plate which 

 is broader than long and triangular in shape with the angles rounded. 

 This plate separates the two radial shields of each pair for a small 

 part of their length at their proximal extremities. A few other 

 very small rounded plates also appear here and there, especially 

 toward the distal border of the five primary radials. The radial 

 shields are not larger than these latter ; they are triangular with the 

 proximal angle very obtuse and rounded, or sometimes irregularly 

 quadrangular, and almost as long as broad; their length exceeds a 

 third of the radius of the disk. The two shields of each pair are in 

 contact throughout the greater part of their length. The radial 

 papillae are rather long, somewhat flattened and broadened, and 

 broadening especially in their distal half, in such a way as to assume 

 a more or less spatulate form ; these papillae are very close together. 



In specimen B the plates of the dorsal surface of the disk are more 

 numerous and the large plates are relatively smaller than in A. The 

 six primary plates are of the same size and their shape is rounded ; 



