﻿139 Florida Oligocene Shells 



groovings visible only with a lens. Longitudinal sculpture of 

 strongly marked riblets (ten on the body whorl) which are very 

 oblique on the dorsal side of the shell. Aperture oval ; canal 

 short. Length of shell 3 ; greatest width 2 mm. 



Oak Grove, Santa Rosa County, Florida. 



Mr. Aldrich's collection. 



Dedicated to Professor Thomas Watson of the University of 

 Virginia. 



Nassa BerthcB, n. s. 

 PI. V, fig. 7. 



Shell tapering regularly to an acute apex ; whorls eight in 

 mature shells, the two nuclear being smooth, the subsequent 

 whorls bearing each about twenty very regular, straight trans- 

 verse ribs, extending the full length of the whorls ; beneath the 

 suture the ribs are cut by an incised spiral line so that their ends 

 appear as a series of beads crowning the summit of each whorl ; 

 lower half of the body-whorl with about six spirals which become 

 obsolete above the center of the whorl ; aged shells have the outer 

 lip lirate within and the callus of the columella plicate. 



Height of shell 13 ; of aperture 5 ; greatest width 5.5 mm. 



The striking features of this unusually beautiful A T assa are 

 the regular and elegant riblets and the absence of spirals except 

 just beneath the suture and on the base of the body-whorl. 



Oligocene of the Chipola marls, Bailey's Ferry, Calhoun 

 County, Florida and of the Oak Grove sands of Santa Rose 

 County, Florida. 



Named in honor of Dr. Bertha Stoneman of the University of 

 South Africa. 



Cornell University and Mr. Aldrich's collection. 



Nassa Dalli, n. s 



PI. V, fig. 8. 



Shell rather small with seven whorls, of which the first two 



are smooth, the remainder sculptured ; spire acute: transverse 



sculpture of fine sub-equal threads (visible without a lens) with 



