Wachsmuih and Springer — Revision of the genus 



re, the beveling and constricting of the upper 

 edges of the basals, gives to the basal portion the appearance 

 of enclosing the cup which is formed by the radials. It differs 

 from those species also in the highly arched surface of the first 

 radials and the deep sutures between them, which give to the 

 upper part of the cup its crenulated aspect. Also in the cari- 

 nated surface. From B. typus, it further differs in the mode 

 of attachment of the free radials and arm joints, the rim-like 

 projection at the upper face of each plate, and in the strongly 

 pentagonal and crenulated column. 



It differs from our species B. Pourtalesi, in most of the above 

 particulars and in the proportionally smaller size of its free 

 radials, in the succession of the syzygial joints, and in the sim- 

 plicity of the pinnules. 



The specimen from which our description is made, is in a 

 most perfect state of preservation, showing column, calyx, pro- 

 boscis, and arms, the calyx being plump and every plate ex- 

 actly in position. 



Geological position and locality: from a thin cherty layer 

 near the middle of the Upper Burlington limestone, Burlington, 

 Iowa. Collection of Charles Wachsmuth. 



Belemnocrinus Pourtalesi, n. sp. 



Smaller than either of the other described species. The 

 column is unknown, but, from the impression of its atl 

 to the lower excavated parts of the basal plates, it was evidently 

 more or less pentagonal. 



Calyx low, about two thirds as wide as high, basal cup sub- 

 globose, constricted and truncated above and deeply excavated 

 below for the reception of the column. The portion composed 

 of the first radials and anal plate, being a little less in diameter 

 at its junction with the basals, expands upward and gives to 

 the whole calyx a form somewhat urn-shaped. 



Basal plates nearly uniform in size, two-thirds as wide as 

 -i tly widest above, strongly convex and bulging in the 

 middle, being curved somewhat like the staves of a cask, upper 

 feces nearly truncate, lower faces truncated with abruptly 

 rounded edges and excavated. They are heavy plates, solid 

 below, leaving onlv a small perforation connecting with the 

 column. 



Radials, four. The first radials, alternately arranged with 

 the basals, are only one-third of their size, wider than long, 

 quadrangular, closely join.', I .it tin- 1 tt-ni -utuiv-. :un! -l'-i itly 

 set in from the outer upper edge of the basals, leaving a rather 

 deep transverse suture. Second and third radials as wide as 

 the first and more than twice as wide as high. Fourth radials 

 larger than the others, pentagonal, supporting- upon their upper 

 sloping faces the free arms. 



