NAVICELLA. NERITINA. 49 



LES NEEITACES. 



NAVICELLA. FLUVIATILE. 



Elliptical or oblong, concave beneath ; spi7'e erect ; 

 margin always inflected; outer lip flattened, 

 acute, angulated, and destitute of teeth ; aper- 

 ture provided with a solid flat operculum, 

 having a lateral point, 



N. ELLTPTiCA. Smooth, shining, spotted 

 and streaked with blue, purple, or brown, covered 

 with an olivaceous epidermis ; spire curved, promi- 

 nent, extending beyond the margin ; diam. |. 

 W. 37. 9. 



NERITINA. FLUVIATILE. 



Thin, semi-globose or ovate, flattened below ; with- 

 out an umbilicus ; aperture semi-circular ; inner 

 lip flattened, and reflected on the columella, 

 sometimes slightly crenated ; outer lip destitute 

 of teeth, or crenulations on its internal face ; 

 aperture provided with an operculum, having a 

 lateral point. 



N. ZEBRA. Oblong-globose, glabrous, fulvous 

 red, with longitudinal flexuous very oblique black 

 lines ; aperture white; lip denticulated; diam. f. 

 W. 35. 18. 



N. CORONA. Oblong-globose, striolate, black; 



D 



