23-4 PALEONTOLOGY OF ILLINOIS. 



Sphenopoterium oompressum, M. and W. 



PI. IT, Fig. la, 16, lc. 



Sphenopoterium compressam, Meek and Worthen, Oct., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 448. 



Compressed-cuneate, wider than high, carinate on each late- 

 ral margin, and sulcate between the cells on each compressed 

 side ; base apparently retaining remains of a scar of attach- 

 ment. Cells three or more, arranged parallel to the greater 

 transverse diameter of the body, rather deep and conical; 

 walls thin. Surface presenting a fine shagreen-iike appear- 

 ance from the anastomosing of the striae. Length or height, 

 about 0.55 inch; greatest breadth, near 1 inch; thickness, 

 0.38 inch. 



It is possible this may be a variety of the preceding species, though its more 

 compressed form, thinner walls and lateral carinae, give it a very different ap- 

 pearance. Its surface striae are also finer and more broken up into granules. 



Locality and position : same as last. 



RADIATA. 

 EOHINODERMATA. 



CRINOIDEA. 

 Genus CYATHOCRINUS, Miller, 1821. (See p. 175.) . 

 Cyathocrinus angulatus, M. and W. 



PL IV, Fig. 4. 



Cyathocrinus angulatus, Meek and Worthen, Sept., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 391. 



Body rather large, strong and robust, basin-shaped below the 

 arms, wider than high, truncated below, and expanding rapidly 

 upwards; composed of very thick, nearly smooth, or subgran- 



