The Fauna of the Maxville Limestone. 407 



1886. Capulus acutirostris. Claypole, Proc. and Coll. Wyo. Hist, and 

 Geol. Soc, Vol. II, pt. II, p. 246. 

 Lower Coal Measures : Wilkesbarre, Pennsylvania. 

 1890. Capulus acutirostris. Keyes, Am. Geol., Vol. VI, p. 9. 

 1890. Capulus acutirostris. Keyes, Proc. Acad. Nat. Sci. Phil., p. 170. 

 Keokuk group : Warsaw and Nauvoo, Illinois. 

 St. Louis limestone : Spergen Hill and Bloomington, Indiana ; 

 Tuscumbia, Alabama. 

 1892. Orthonychia acutirostre. Keyes, Am. Geol., Vol. X, p. 276. 

 1894. Orthonychia acutirostre. Keyes, Mo. Geol. Surv., Vol. V, p. 190, 

 pi. 54, figs. 2a-c. 

 Keokuk limestone and shale : Warsaw and Nauvoo, Illinois. 

 St. Louis limestone : Spergen Hill and Bloomington, Indiana ; Tus- 

 cumbia, Alabama. 

 1897. Capulus acutirostris. Weller, Trans. N. Y. Acad. Sci., Vol. XVI, 

 p. 268. 

 Batesville sandstone : Batesville, Arkansas. 

 1906. Orthonychia acutirostre. Cumings, Ind. Dept. Geol. Nat. Res., 

 30th Ann. Rep., p. 1335, pi. 23, figs. 14, pi. 25, figs. 5, 13-15. 

 Salem limestone: Spergen Hill, Bloomington, Indiana; Illinois; 

 Alabama. 

 1909. Orthonychia acutirostris. Grabau and Shimer, N. A. Index. Foss., 

 p. 688, figs. 976, 977. 

 Keokuk and Warsaw : Illinois, Indiana, Alabama. 

 St. Louis : Indiana, Illinois. 

 Chester : Arkansas. 

 Coal measures : Pennsylvania. 



Description. — ''Shell below medium size, rather slender, 

 strongly arcuate, forming from one to one and one-half volu- 



FiG. 30.- — Orthonychia acutirostre. A slightly restored drawing of an 

 individual, showing the promi-nent ridge on the dorsal side. En- 

 larged two diameters. 



■ tions ; posterior side for some distance from apertural margin 

 nearly straight. Spire laterally more or less compressed ; some- 



