9 



which arrangement gives to this ray six arms. The species evi- 

 dently has either twenty-four or twenty-six arms. The arras are 

 in clusters of two or three that project and have depressed inter- 

 spaces, that are most conspicuous on the vault, but give a very 

 irregular outline to the top of the calyx. 



In each of the regular interradial areas there are four plates. 

 The first is very large: it is followed by two plates of unequal 

 size, and above these there is a smaller one. The azygous area 

 is much elongated and contains seven plates. The first one is in 

 line with the first primary radials, and nearly as large as any of 

 them. It is followed by three plates sub-equal in size and about 

 as large as the first. These are followed by two plates, one quite 

 small and the other about as large as those in the second range. 

 Above these there is an elongated plate in the fourth range that 

 sends an angle high between the quaternary radials, and to near 

 the top of the calyx. 



The vault is convex, irregular, depressed in the interradial areas 

 and covered with remarkably large, polygonal, peculiar, nodose 

 plates, dome of the plates bear a large, wedge-shaped spine; 

 others bear one, two or three nodes, more or less irregularly de- 

 fined. The proboscis is subcentral, but broken off in our speci- 

 men. Three elongated plates with nodes near the upper end may 

 be seen over the azygous ai'ea in figure 7, and two orifices pene- 

 trating the vault at their lower angles. One elongated plate may 

 be seen in figure 8 separating the four armed series with two 

 orifices penetrating the vault at the lower angles. And the plate 

 separating the four armed from the six armed series is one-half 

 longer than either one shown in the illustrations. Two pores pene- 

 trate the vault between each of the arms, except the quaternary 

 series, and, therefore, there are forty of these so-called ovarian 

 orifices. 



This species bears more resemblance to Balocriniis riiriosuft 

 than to any other heretofore described, though the vault differs 

 so much from that, it will be wholly unnecessary to institute any 

 coDparisou. The difference in the form of the calyx in the two 

 species will account for the variations in the size and shape of 

 the plates so far as the basal and radial series extend, but the 

 differences in the number of interradials and shape of the areas 

 will always constitute specific characters. The sharp radial plates 

 in B. cnriosns and depressed spaces between the bunched radial 

 series in this species are not to be overlooked. 



Found by Prof. A. G. Wetherby in the Kejkuk Group, on 

 Little Barren River, in Kentucky, and now in the collection of 

 Wm. F. E. Gurley. 



