There are three plates in each regular interradial area, one 

 large plate followed by two small ones, that are cut off from 

 any connection with the vault. The azygous area contains 

 eight plates. The first one is in line with the first primary 

 radials and fully as large. It is followed by three large 

 plates, subequal in size, in the second range, and these by 

 three small plates, in the third range, that are surmounted by a 

 single plate in the fourth range that unites with two plates 

 belonging to the vault. 



The vault is somewhat elevated over the ambulacral open- 

 ings, and convex toward the center, which bears a proboscis, 

 that is broken off in our specimen just above the summit. It 

 is covered with numerous, convex, polygonal plates, some of 

 which bear central nodes. We are unable to discover any 

 ovarian pores. It is probable, that, in some species, the 

 ovarian pores were on the sides of the arms near the calyx, 

 if the pores are correctly named. We know, that in some genera, 

 as in Dolatoorinus, they vary in their places of exit from in- 

 terradially on the vault to the base of the arms, and we see 

 no reason why the channels may not have been carried up the 

 ambulacral furrows one or more plates beyond the commence- 

 ment of the free arms. 



This species is distinguished by its general form, by having 

 only eighteen arms, three regular interradials cut off from the 

 vault and eight azygous plates, the last one connecting with 

 the vault. These peculiarities do not exist in any other de- 

 scribed species. It is probably as closely related to B. labellum, 

 from the Keokuk Group, as to any other species, though a 

 glance will distinguish them on account of the general form 

 and surface of the plates, beside the interradial areas are not 

 alike, and, in that species, the azygous area is cut off from 

 the vault, and in this species it is connected with the vault. 



Found by Dr. M. N. Elrod in the St. Louis Group, at 

 Lanesville, Indiana, and now in the collection of Wm. F. E. 

 Gurley. 



