49 



prominent tubercles on the body whorl, and one re- 

 volving near the base of* each whorl of the spire; su- 

 ture profoundly impressed, margined by an obtuse 

 subnodulous prominent line; lines of growth very ob- 

 lique and prominent; obscure spiral strise; epidermis 

 olive; within bluish, often with purple bands. 



OBSERVATIONS. 



A beautiful species when perfect, occurring in 

 vast abundance on the masses of calcareous rock, 

 which have fallen from the strata above, into the 

 Alabama river, at Claiborne. I found it living only 

 in such situations, and exclusively within a range of 

 six or eight miles. In the Tombeckbe or Black War- 

 rior rivers, I never observed a specimen of it. 

 although I searched particularly for it on the rocks at 

 St. Stephens. 



MELANIA EXCURATA. 



Plate lY.—Fig. 6. 



DESCRIPTION. 



Shell subulate, with a spiral band of slightly obhquc 

 subcompressed tubercles on the base of the inferior 

 whorls; above this is a prominent line with a slight 

 intervening channel; volutions towards the apex 

 nearly entire; base with three prominent lines, the 

 superior one largest; the third hardly prominent and 

 approximate to the middle one. 



E 



