GASTEROPODS. U7 



Bellerophon bilobatus? SOWERBY. 

 Plate li, fig. 2. 



Bellerophon bilobatus Sowerby, 1839 : Murchison's Sil. Syst., p. 643. 

 Bellerophon bilobatus Hall, 1847 : Pal. New York, vol. I, p. 184. 



Shell of medium size, rather rapidly expanding to the aper- 

 ture. 



Horizon and localities- Lower Silurian, Trenton lime- 

 stone: Glencoe (St. Louis county). 



Bellerophon panneus WHITE. 



Plate 1, fig. 6. 



Bellerophon panneus White, 1862: Proc. Boston Soc. Nat. Hist , vol. IX, 



p. 21. 

 Bellerophon panneus Keyes, 1889: Proc. Acad. Nat. Sci., Phila., p. 297. 



Shell globose, composed of about four volutions, all of 

 which are visible in the rather small, very deep umbilici ; per- 

 iphery somewhat flattened, with a very prominent longitudinal 

 carina ; the surface marked by sharp, equidistant costse pass- 

 ing transversely across the whorls from the large median ridge ; 

 transverse elevations somewhat undulating and irregular, and 

 bending forward slightly as they leave the central prominence ; 

 finer lines of growth are also visible between the costse. 



Horizon and localities. Lower Carboniferous, Kinderhook 

 beds: Burlington ( Iowa ); apparently fragments also of this 

 species from Hannibal. 



Bellerophon bilabiatus WHITE & WHITFIELD. 

 Plate 1, fig. 3. 



Bellerophon bilabiatus White & Whitfisld, 1862 : Proc. Boston Soc. Nat. 



Hist., vol. VIII, p. 304. 

 Bellerophon bilabiatus Keyes, 1891: Proc. Acad. Nat. Sci., Phila., p. 297. 



The deeply and broadly emarginate lip, the nearly glabrate 

 surface and a sharp, narrow, median carina readily distinguish 

 this form from the associated speci.es of the genus. 



Horizon and localities. Lower Carboniferous, Kinder- 

 hook group: Chouteau Springs ; Burlington limestone: Lou- 

 isiana. 



