296 PALEONTOLOGY OF ILLINOIS. 



POTEKIOCRINUS PopENSis, Worthen. 



PI. XXIX. Fig. 12, 



Poteriocrinus Popensis, WOBTHEN, February. 1882. 



Bulletin No. 1, of the Illinois State Museum of Natural History, p. 23. 



Boby small, obconic, gradually swelling from the base to the sum- 

 mit of the radial plates, where it is about once and a half as wide as 

 long, composed of smooth, slightly protuberant plates. The basals 

 project about one-half their length beyond the column, and form a 

 low pentagonal cup. 



Subradials on the anterior side hexagonal, about as wide as long. 

 Eadials pentagonal, once and a half as wide as long, and truncated 

 squarely across their upper margins for the reception of the brachial 

 plates. 



Brachials pentagonal, length and breadth about equal, rounded 

 externally, and sharply angular above, supporting on their sloping 

 sides the first divisions of the rays. All the arms on the anterior 

 side divide again on the seventh, eighth or ninth plate above the 

 brachials, and one of them gives off a second branch on the eighth 

 plate, while the others are not preserved beyond the second division 

 above the brachials. The arms are composed of short wide plates, 

 the two first above the brachials being about twice as long as the 

 succeeding ones, and all a little wedge-shaped. The arms are only 

 about half as wide above the second bifurcation as below. Anal 

 plates unknown. 



Column round, composed near the base of thick and thinner plates 

 alternately arranged. 



This species is related to Pot. (Scaph.) Randolphcnsis, Geol. Surv. 

 of 111., Vol. 5, page 551, but differs in its wider and more nearly 

 parallel arm plates, as well as in the bifurcation of the arms. 



Position and locality: Chester limestone, Pope county. 111. 



No. 2,454, Illinois State collection. 



POTEBIOCKINTJS OsAWENSis, Worthen. 



PI. XXIX, Fig. 2. 



Poteriocrinus Oknwensis, WOBTHEN, February, 1882. 



Bulletin No. 1, of the Illinois State Museum of Natural History, p. 24. 



Body of medium size, wider than high to the top of the radial series, 

 composed of smooth, slightly convex plates. 



