DESCRIPTIONS OF SPECIES. 463 



Strophostylus subovatus Woi-then? 



PL X, figs. 3, 3a. 



1873. Naticopsis subovatus. Wortlien, Geol. Surv. Illinois, Kept., vol. 5, p. 595, pi. 28, fig. 9. 



I'^pper Coal Measures: Lasalle, 111. 

 1898. Brophostyhis suhovahis. Weller, U. S. (ieol. Surv., Bull. No. 153, p. 615. 



This identitication is based upon a single specimen, which is distinguished from 

 jSt. reme.f \>x its lower spire and more rapidly enlarg-ing- volutions. It is much 

 smaller than fully grown St. xitbovatus, but resembles it in shape closer than any 

 other form with which I am acquainted. 



Locality imd horizon. — San Juan region (station 2217?); middle portion of the 

 Hermosa formation. 



Strophostylus remex White. 



PI. X, figs. 4, 4a, 5 to 5b. 



1876. Naticopsis remex. White, Powell's Rept. Geol. Uinta Mountains, p. 109. 



Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

 1880. Naticopsi-i reme.v. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, p. 

 139, pi. 34, fig. 6a. 

 Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

 1883. Naticopsis remex. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, p. 

 391, pi. .34, fig. 6a. 

 Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

 1891. Naticopsis reme.o. White, U. S. Geol. Surv., Bull. No. 77, p. 24, pi. 3, fig. 10. 



Permian: Military Crossing and Goodwin Creek, Baylor County, Tex. 

 1895. Strophusti/lus remex. Keyes, Missouri Geol. Surv., vol. 5, p. 197, pi. 55, figs. 7a, b. (Date of 

 imprint, 1894.) 

 ITpper Coal ^Measures: Kansas City, Mo. 



This form occurs in the Rico formation at station 2345 and is abundant at station 

 2340. An imperfect .specimen from the Leadville region (station 2273) seems to 

 belong to this species. Some of the smaller individuals approach St. nanuts. 



Locality and horizon. — San Juan region (stations 2340, 2345); Rico formation. 

 Leadville district (station 2273); Robinson limestone. 



NATICOPSIS McCoy, 1S44. 

 Naticopsis altonensis McChesnej'. 



1865. Natiea altonensis. McChesney, Illustrations New Spec. Foss., pi. 2, figs. 14a, b. 



Coal Measures: Alton, 111. 

 1868. Naticopsis altonensis. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 50, pi. 2, figs. 14a-c. 



Coal Mea.sures: Alton, 111. 



