98 PALEONTOLOGY OF ILLINOIS. 



"Body below the arms very broadly basin-shaped, or de- 

 pressed hemispheric, with the upper margins inflected; articular 

 scar for the column attachment sharply impressed, extending 

 one-half or two-thirds the diameter of the basal plates. 



Basal plates pentagonal, obtusely angular above, forming by 

 their union a pentagon with scarcely concave margins. Sub- 

 radial plates exceedingly large, extending from the edge of the 

 column to near the top of the first radial plates, three sub- 

 pentagonal and two heptagonal (or hexagonal from the straight- 

 ness of the lower sides), length somewhat greater than breadth. 

 First radial plates proportionally small, sub-triangular; the 

 lateral edges of the adjacent plates slightly truncating each 

 other. First anal plate large and massive, pentagonal, resting 

 between the two heptagonal sub-radials, and supporting one 

 side of the adjoining first radial plate. The two remaining anal 

 plates, (all of which are seen in the specimen,) are smaller and 

 hexagonal. 



Arms and column unknown. Surface of plates depressed con- 

 vex, sutures distinctly marked. The body plates are very 

 massive, the internal cavity being less than half the whole 

 iiameter." 



Position and locality: Keokuk limestone, Keokuk, Iowa. 



The specimen figured is in the collection of A. H. Worthen. 



EUPACHYCRINUS? SANCTI-LUDOVICI. (sp. UOV.) 



We have obtained from the St. Louis quarries some crushed 

 specimens of a form apparently belonging to the above named 

 genus, none of which are quite well enough preserved to admit 

 of a clear and full diagnosis, but differing so much from all 

 other crinoidal forms known from this horizon, that the crushed 

 specimens may be easily recognized when the general form is 

 known. 



Body of medium size, basiii-shaped, base depressed, the under- 

 basals concealed in the basal concavity. Basals prominent, the 

 lower angles curving upward into the basal depression, their 

 upper angles extending nearly to the summit of the first radial 

 plates. First radial s pentagonal, their lower angles fitting into 

 the depression between the bawals, widest at their summits where 

 they are squarely truncated for the support of the second 



