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those resembling it, by a sinus on the right margin of 

 the aperture, only visible when the mouth is quite per- 

 fect, (which seldom occurs), and not existing in any 

 other species of shells of a similar form. They are all 

 marine shells, more or less striated, or transversely ca- 

 rinated, but none of the species known possess vertical 

 ribs, thickened bands, or spinous tubercles; the edges 

 of the aperture are separated at the upper part, and ne- 

 ver reflected outwards; they are of a very long, turreted, 

 spiral form, attenuated to a sharp point; and when the 

 lip is perfect, it exhibits a sinus between the upper cari- 

 nations. They possess an orbicular, horny operculum 

 Turritella duplicata Turritella brevialis 



terebra bicingulata 



imbricata trisulcata 



replicata • • exoleta 



fuscata carinifera 



cornea australis 



Turritella Virginiana. 

 [There are also twelve fossil species.] 



