27 



area ;upports, on each upper sloping side, three secondary ralials, 

 which gives to this ray two arms. In each of the lateral rays and 

 in the ray on the right of the azygous area the third primary radial 

 supports, upon one upper side, three secondary radials and upon the 

 other two, the last one being axillary and supporting, on each upper 

 side, two tertiary radials, which gives [to each [of these rays three 

 arms. In the ray on the left of the azygousarea the third primary 

 radial bears, upon each upper sloping side, two secondary radials, 

 the last being axillary and supporting, on each upper sloping side, 

 two tertiary radials, which gives to this ray four arms. There are, 

 therefore, fifteen arms in this species. The [arm formula is 3-J-3-f-2 



In each regular interradial area, there are three plates, one in the 

 first range followed by two elongated plates, in* the second range, 

 that unite with the plates of the vault. In the azygous area there 

 are seven plates. The first one is in line with the first primary ra- 

 dials and about the same size. It is followel by three plates, in the 

 second range, and these by three plates, in the third range, all three 

 of which unite with the plates of the vault. 



Vault pyramidal by reason of the depressed interradial areas, 

 larger than the calyx, and bears a large central proboscis. It is 

 covered by large convex, polygonal plates. 



This species is most nearly related to B. reserrdtits, above de- 

 scribed, from which it is distinguished, by the hexagonal disc, form- 

 ed by the basal plates, instead of a round expanding cup; by the 

 azygous area, which has seven plates, three of which unite with the 

 plates of the vault, instead of four plates, only one of which con- 

 nects with the vault; by the larger vault which is covered with 

 larger and more convex plates; and by the arm formula which is 

 3+3+2+3 4, instead of 3 4 2 3 3. There are minor differ- 

 ences as may be seen by comparing the descriptions. It need not 

 be compared with any other species. 



Found by R. A. Blair, in the Burlington Group, near Sharon, in 

 southwestern Missouri, and now in the collection of S. A. Miller. 



