21 



the secondary radial plates and connect with the plates of the 

 vault. There are eight or more plates in the azygous area. 

 The first one is in line with the first primary radials and of 

 about the same size. It is followed by a range of three plates 

 and above the plate on the left there is a small intercalated 

 plate, and, above these, there are three plates that connect 

 with the plates of the vault. In fact, they interlock with the 

 plates of the vault so that there is no distinct line between the 

 plates of the calyx and those belonging to the vault. There 

 is also a minute plate intercalated above the second range on 

 the right, as shown on the specimen preserving the plates, 

 but it is not indicated on the cast. There is a little difference, 

 in the upper part of the azygous areas, between the cast and 

 the specimen having the plates, and the cast indicates nine 

 plates in the area; but, on the whole, we think the cast be- 

 longs to this species. 



The vault is convex and is covered with convex polygonal 

 plates and bears a central proboscis that is broken off from our 

 specimens. The cast shows the ambulacral channels are flat- 

 tened on the superior side, but have a depth equal to the flat- 

 tened diameter. The ambulacral openings are within the mar- 

 gin of the stellate projections of the radials and appear to be 

 directed upward, notwithstanding that the lower side of the 

 radials is projected horizontally, and the cast shows the am- 

 bulacral openings to be directed horizontally. 



This is a very distinct and peculiar species that can hardly 

 be compared with any other. It would seem to be as near B. 

 astencus as to any other species, though that species has 

 twenty arms, rounded basals, and altogether different regular 

 areas and azygous area. 



Found by R. A. Blair, ng the Burlington Group, at Sedalia, 

 Missouri, and now in the collection of S. A. Miller. The spe- 

 cific name is intended as a compliment to the accomplished 

 daughter of R. A. Blair, who has assisted her father so much 

 in collecting and making known the fauna of the Chouteau and 

 Burlington Groups of Missouri. 



