570 PALEONTOLOGY OF ILLINOIS. 



more produced, with only two or three slender spines on 

 their margins; costae more even on the front portion of the 

 shell, the spines less numerous and more slender, and with- 

 out concentric wrinkles. The dorsal valve is concave in 

 the visceral region, nearly quadrangular in outline, the 

 front slightly sinuous, and sharply recurved on the margin, 

 reniforni processes smaller than in P. co8tatu$, more eleva- 

 ted, and nearer the hinge line. Cardinal process trilobed. 



Locality and position Upper Coal Measures, La Salle, Illinois. 

 CHONETES SMITHII, N. and P. 



PL 25, Tig. 11. 



Choneies Smithii, NORWOOD and PKATTEN, 1855. Jour. Acad. Nat. Sci., Phila., Vol. Ill, new 8r., p. 

 24; pi. 2, fig. 2, a, b, c. 



Position and locality Eoof of Belleville coal ; St. Clair county, Illi- 

 nois. 



Genus HEMIPROOTTES, Pander. 

 HEMIPRONITES CRASSUS, M. and H. 



PI. 15, Fig. 12. 



Orthisina crassa, MEEK arid HAYDEN, 1858. Proceed. Acad. Nat. Sc., Phila., p. 260. 



Orthis Laxattensis, 1860, McCHESNEY. New Pal. Foes., p. 32 ; pi. I, fig. 6, a, b. 



O. Richmondi, McCHESNEY. Ib. ; fig. 5, a, b, c. 



Hemipronites crassus, MEEK and HAYDEN, 1864. Paleont. Upper Missouri, p. 26; fig. 7, a, b, e, d. 



Position and locality Abundant in upper Coal Measures ; La Salle, 

 Illinois. 



Genus ATHYRIS, McCoy. 



ATHYRIS SUBTILITA, Hall's (sp.) 



PL 25, Fig. 14. 



Terebratula subtilita, HALL. Stansbury's Grt. Salt Lake Beport, p. 409 ; pi. IV, fig. 1, a, 6,and 2, a, b. 

 Spirigera subtilita, MEEK and HAYDEN, 1859. Proceed. Phila. Acad. Nat. Sci., p. 20, etc. 

 Athyris subtilita, NEWBERRY, 1861. Ives' Colorado Report, p. 126. 



Position and locality Abundant throughout the Coal Measures. 



