NERITELLA. 39 



lum, reclivata andjpic^a are marine, and there- 

 fore should not have been included ; one, Jay- 

 ana, is fluviatile, but belongs to the European 

 group undoubtedly ; and one, Californica, is 

 marine, and belongs to the Philippine Islands 

 group of species. The remaining species I 

 describe. 



1. NERITELLA SHOWALTERI, Lea, 



Plate 16, fig. 2. 



Shell smooth, rounded, semi-transparent, 

 yellowish horn-color; spire very much de- 

 pressed; sutures slightly impressed; whorls 

 three, inflated; aperture semirotund; inner 

 lip dilated, white, thickened, without teeth 

 and incurved; outer lip acute, dilated and 

 thin. Operculum — ? 



Diameter 5, alt. 4*5 mill. 



Coosa River, Shelby Co., Alabama. 



A very rare species, of which Dr. Lea only 

 received four specimens, one of which he 

 obligingly presented to the Academy of Natu- 

 ral Sciences. 



