TRANSACTIONS OF WAGNER 

 I 3 66 



TERTIARY FAUNA OF FLORIDA 



nearly circular outline. Alt. 28, Ion. 28, diam. 30 mm. The largest specimen 

 observed has a length of 42 and a diameter of 35 mm., while a specimen of 

 P. pensylvanicus of the same size has a diameter of only 25 mm. 



The cardinal teeth of the fossil are also much more clear-cut than in the 

 recent shell, in which the two smaller cardinal teeth are usually very obscure or 

 even obsolete in adult specimens. 



Phacoides (Here) Glenni n. sp. 

 PLATE 50, FIGURE 17. 



Oligocene of the Chipola beds on the Chipola River, and of the lower bed 

 at Alum Bluff on the Chattahoochee River, Calhoun County, Florida ; Burns 

 and Ball. 



Shell of moderate size and convexity, solid, polished, with small prosogyrate 

 rather elevated beaks, rounded or subovate outline, and strongly marked dorsal 

 areas; the young begin with a subrhomboidal shell, in which the projecting 

 anterior and posterior ends recall P. cariniferus; the exterior is elegantly and 

 rather closely concentrically rippled ; the lunule is deep and cavernous, much 

 more excavated in proportion than in the adult, and the dorsal areas are larger 

 in proportion to the whole shell. In the course of growth the concentric sculp- 

 ture becomes feebler and more distant, the strong, cord-like carina below the 

 centrally convex anterior dorsal area becomes less conspicuous, and the outline 

 of the valve changes to subovate, rather higher than long, and the lunule is so 

 obscured by the gyrate beaks that it is no longer noticeable. An average speci- 

 men measures : alt. 32, Ion. 30, diam. 16 mm. 



The margins are elegantly minutely crenulate. The shell is named in honor 

 of Professor L. C. Glenn, who has done much work on the Tertiaries of Mary- 

 land and Virginia. 



Phacoides (Here) tithonis n. sp. 

 PLATE 50, FIGURE 10. 



Oligocene of the Bowden, Jamaica, marl, collected by Messrs. J. B. Hen- 

 derson, Jr., and Charles T. Simpson. 



Shell small, rotund, with rather prominent beaks, the dorsal areas not dis- 

 tinguished by sculpture and indicated only by faint, broad, radial sulci ; lunule 

 small and deep, no escutcheon visible ; surface with profuse, elevated, rather 

 unevenly spaced, concentric lamellae ; hinge well developed ; margins minutely 

 crenulated. Alt. 4.0, Ion. 4.5, diam. 3.8 mm. 



This little shell, represented only by a single valve, is apparently the pre- 



