1894. PROCEEDINGS OF THE NATIONAL MUSEUM. 287 



the lieight, where best developed, is greater than the breadth. The 

 dorsal surface of this portion is completely covered by flat, imbricated, 

 rounded, and angular plates, each of which bears a large number of 

 very minute, sharp, conical spiuules, which are closely arranged over 

 most of the surface, but on the sides of the rays they often form two or 

 three small transverse rows on each plate. With these spinules on the 

 plates there are also many minute pedicellaria\ 



Low down on the sides of the rays, and especially on the distal por- 

 tion of the genital region, the plates form regular transverse series or 

 bauds with naked integument between them; each of these bands 

 corresponds with one of the adambulacral plates. The last of the bands 

 are imperfect, or represented by only a few plates on the dorsal surface, 

 and cease entirely opposite about the twenty-fifth adambulacral plate. 

 On the distal part of the arm the thin membrane is crossed by a broad 

 baud of minute pedicellaria?, a band corresponding to each adambu- 

 lacral plate. Ajucal plate not much enlarged, short, obovate, obliquely 

 truncate at the end, about as long as broad; its si)ines have been 

 rubbed off from the only one preserved. 



Along each side of the ray there is a row of long, slender, lateral 

 spines apparently arising from small tubercular marginal plates, which 

 are mostly coalescent with the outer end of the adambulacral plates 

 and usually might be described as a part of them. These marginal 

 spines, on the distal part of the rays, occur opposite the alternate 

 adambulacral plates, but along the genital region they occur only oi»po- 

 site every third plate. 



The adambulacral plates are somewhat longer than broad, except at 

 the base of the ray, and but little emargiuate on the furrow-margin. 

 Each plate bears a long, slender, fluted spine on the actinal surface, 

 similar to the adjacent marginal spines, and on alternate plates there 

 is usually a much smaller, acute, more or less inclined furrow-spine 

 standing just in front of the larger one, but these are mostly absent or 

 rudimentary on the distal half of the ray. There are no transverse 

 furrow spines, unless the spines just described be considered as such. 

 On nine or ten of the basal adambulacral plates the large actinal spine 

 is stout and columnar, with swollen or clavate tips, concave on the 

 summit, and bearing about four to eight blunt papilliv around the nuxr- 

 gin; those nearest the base are shortest and stoutest, the length 

 increasing and the size of the terminal enlargement decreasing gradu- 

 ally on those farther out. 



Radius of disk, 10 mm.; of longest rays (which may have been regen- 

 erated), 95 mm.; length of longest sj)ines, 8 mm. 



Taken in 1884, at station 2220, off Martha's Vineyard, in 1,054 fath- 

 oms, one specimen (No. 7821, U. S. N. M.). 



This peculiar species, in having a more or less distinctly banded 

 arrangement of the plates on the genital region of the rays, approaches 

 the restricted genus Brisinga, but its affinities are decidedly with 



