﻿153 Florida Oligocene Shells 35 



Length of largest shell 9 ; height 7 ; diameter of one valve 2 mm. 

 The usual size is, however, much smaller. 



Chipola marls, Bailey's Ferry, Florida. 



Cornell University collection. 



This very elegant species resembles C. magnoliana Dall from 

 the Upper Miocene of Magnolia, North Carolina, but the Chipola 

 species can be distinguished at a glance by its much more in- 

 equilateral form. 



Phacoides prunoides , n. s. 

 PI. IX, fig. 3. 



Shell resembling P. primus Dall of the Miocene of Maryland 

 but more inequilateral, with a decided sulcus extending from the 

 beak to the margin of the shell, and with more recurved beaks. 

 Concentric sculpture of regular, low, flat-topped ribs with very 

 narrow inter-spaces ; inner margin of shell finely crenulated. 



Height of shell 7 ; length 7.5 ; diameter 4 mm. 



Chipola marls, Bailey's Ferry, Florida. 



Cornell University collection. 



Phacoides actiuoides, n. s. 

 PI. IX, fig. 4. 



Shell resembling P. aciinus Dall from the Oligocene of Bow- 

 den, Jamaica but larger, more inequilateral, and with more 

 strong^ recurved beaks than that species from which it also dif- 

 fers in sculpture. The Oak Grove species is a plump, fairly solid 

 shell, with the anterior end longer than the posterior but com- 

 pressed as though pinched, lunule cordate, distinct ; shell with 

 three types of sculpture viz : very near the beak are about three 

 concentric lamellae which form the only sculpture for a distance 

 of about half a millimeter ; beyond this radial ribs begin to ap- 

 pear and form with the succeeding half-dozen concentric lamellae 

 a beautiful cencellation like that over the whole disc of the Plio- 

 cene P. waccamawensis Dall. This cancellation continues for a 

 distance of about one millimeter after which the concentric 

 lamellae become fainter aiid more irregular and the six or seven 

 primary ribs continue only faintly to the ventral margin of the 



