17 



three arms. The other lateral ray is constructed, in like man- 

 ner, and bears three arms. There are, therefore, fifteen arms 

 in the species. 



There are two regular interradials in each area, one follow- 

 ing the other and cut off from the vault by the union of the 

 secondary and tertiary radials. In the azygous area there are 

 four plates. The first is in line with the first primary radials 

 and of about the same size, It is followed by three plates in 

 the second range, the middle one of which is large and elon- 

 gated and extends to the plates of the vault. 



The vault is highly convex, covered with polygonal plates 

 and bears a very small, subcentral proboscis, which is broken 

 off at the top of the vault in our specimen. 



This species is quite peculiar in its form and structure and 

 the first species ever described, from the Burlington Group, 

 which possessed fifteen arms. 



Pound by Mr. C. S. Hodgson, in the Burlington Group, in 

 Adams county, Illinois, and now in the collection of S. A. Miller. 



BATOCRINUS NANUS, n. sp. 



Plate J, Fig. 42, azygous view; Fig. 43, opposite side; Fig. 44, 



summit view. 



Species small, below medium size, biturbinate, calyx larger 

 than the vault. Calyx obconoidal, somewhat pentagonal, in the 

 superior part, by reason of a flattening or slight depression of 

 the interradial areas; about one-half wider than high. Radial 

 ridges undefined. Plates slightly convex; surface finely granular. 



Basals form a low hexagonal disc, but are so injured in our 

 specimen that a particular definition cannot be given of them. 

 Pirst primary radials large, nearly as long as wide, three hex- 

 agonal, two heptagonal. Second primary radials small, from 

 one -half wider to twice as wide as long, quadrangular. Third 

 primary radials about one-half larger than the second, pentago- 

 nal, axillary, and support on each superior sloping side a sin- 

 gle secondary radial. There are, therefore, ten arms in this 

 species. 



All of the interradial areas connect with plates belong- 

 ing to the vault. In the regular interradial areas the first 

 plate is followed by two plates, in the second range, which 

 unite with two plates, about on a level with the top of the sec- 

 ondary radials. The last two plates cover part of the ambulacral 

 canals and, therefore, properly belong to the vault. The first 

 plate, in the azygous area, is longer than a first primary radial, 

 —3 



