282 PALEONTOLOGY OF ILLINOIS. 



Only one of the rays is partially preserved. In this there are 

 five brachials, the last one of which is an axillary plate, and sup- 

 ports the first divisions of the ray, one of which divides again on 

 the third plate, beyond which the arms are not preserved. The 

 arms are composed of long, slender, rounded joints, generally twice 

 as long as wide. 



Column unknown. 



Position and locality : Keokuk limestone, Warsaw, 111. 



No. 2,464, Illinois State collection. 



POTERIOCEINUS NAUvooENSis, Worthen. 



PI. XXVIII. Fig. 10. 



Poteriocrinus Nauvooensis, WORTHEN, February, 1882. 



Bulletin No. 1. of the Illinois State Museum of Natural History, p. 13. 



Body small, cup-shaped; the plates being displaced somewhat by 

 crushing, prevents a complete diagnosis. 



Basals small, and hidden by the first columnar joints. Subra- 

 dials as high or higher than wide, and sharply angular above. 

 Radials pentagonal, wider than long. First brachial quadrangular, 

 second brachial pentagonal, and both as wide or a little wider than 

 the radials below. 



The arms of only one of the rays, the left antero-lateral, is pre- 

 served so that its structure can be made out. This ray divides on 

 the second brachial, and the left branch twice more on the sixth 

 and eighth plate above, while the right branch divides at least four 

 times on the sixth and eighth plates, making at least eight arms 

 to this ray. Anal series cannot be seen clearly enough to be fully 

 determined ; they are apparently arranged as usual in this genus. 



Column round, and composed of thin, unequal joints. 



This species is evidently nearly related to Hall's Pot. (Scapli) 

 aqualis, but differs from that in the relative size of its subnulial 

 plates, and in the number and mode of bifurcation of the arms. 



Position and locality: Keokuk limestone, Nauvoo, 111. 



No. 2,465, Illinois State collection. 



