PHYSA. 131 



6. PHYSA OCCIDENTALIS, Tnjon. 



Plate 6, fig. 18. 



Shell with well-rounded whorls, suture im- 

 pressed ; spire moderate, sometimes short ; 

 apex acute ; texture rather thin, surface 

 crowded with growth-lines, polished, amber- 

 colored ; aperture moderately large, outer lip 

 well rounded, thickened within and tinged 

 with red; columella white, indented, some- 

 what folded, sharp-edged, curved to the right 

 and forwards into a sort of beak at the base. 



Length 18, diam. 11 mill. 



California, Oregon. 



This species, widely diffused throughout the 

 Pacific States, appears to replace the eastern 

 Ph. heterostropha, with which it has been 

 generally confounded. It may be readily dis- 

 tinguished from that shell, however, by the 

 very different form of the columella ; so pro- 

 foundly indented above, and so sharp, twisted 

 and curving forwards towards the base. 

 (47) 10 



