26 



one secondary radial, which is axillary and supports, on the distal 

 side, three tertiary radials, and, upon the proximal side, two ter- 

 tiary radials, the last being axillary and supporting, on each 

 upper sloping side, two quaternary radials, which arrangement 

 gives to this ray six arms. Ia the ray on the left of the azygous 

 area, the third primary radial bears, upon the distal side, two sec 

 ondary radials, the last being axillary and supporting, upon each 

 upper sloping side, two tertiary radials, and bears upon the prox- 

 imal side one secondary radial, which is axillary and supports 

 upon the distal side two tertiary radials, and upon the proximal 

 side a single tertiary radial, which is axillary and supports on 

 each superior side two quaternary radials, which arrangement 

 gives to this ray five arms. There are, therefore, twenty-three 

 arms and twenty-three ambulacral openings to the vault in this 

 species. The arm formula is 6 +4+4+ 4+ 5. 



All of the interradial areas are cut off from the vault. In one 

 of the regular interradial areas there are two plates, one follow- 

 ing the other. In another area there are four plates, one followed 

 by two, in the second range, and one in third. In each of the 

 other two areas there are three plates, one followed by two, in 

 the second range. This is the structure of the type specimen, 

 but other specimens may show some differences in the regular 

 areas. In the azygous area there are seven plates. The first 

 plate is in line with the first primary radials, but not near as 

 wide, though somewhat longer. It is followed by three rather 

 large subequal plates, in the second range, and these by three, in 

 the third range, the middle one of which is quite large and the 

 lateral ones small. This area is entirely cut off from the vault 

 by the union of the quaternary radials. 



The vault is highly convex, or subconoidal, and covered with 

 smooth, polygonal plates. The azygous orifice is subcentral and 

 elevated above the surrounding summit, but there is no proboscis. 

 The ambulacral openings are visible in a summit view. No ova- 

 rian pores discovered. 



This species bears little or no resemblance to any other twenty- 

 three armed species that has been described, either in general 

 form or surface features, and cannot be mistaken for any of them. 

 In its smooth surface it resembles B. dodecadaeiylas, B. rohin- 

 dus, B. oblatuSy B. hageri, B. levis, and other species herein 

 described, though otherwise its affinities would seem to be with 



