1899.] NATURAL SCIENCES OF PHILADELPHIA. 405 



Alt. 31, diam. 13, longest axis of aperture 18^ mm. 



Alt. 32, diam. 13, longest axis of aperture 17 mm. 



Alt. 30|-, diam. 11, longest axis of aperture 16 mm. 



Miami (type locality) and Lemon City, Dade county, Florida. 



Very large series collected by Mr. Rhoads as well as the speci- 

 mens taken by myself are constantly far smaller than the typical 

 form, although they occur in a region where the country rock is 

 limestone. I found only the typical G. truncata at Palm Beach. 

 The small variety seems to be confined to ihe calcareous reirion 

 in the extreme South. 



