190 SYSTEMATIC PALEONTOLOGY 



Florida, and Costa Pica, and in the Pleistocene from Massachusetts to 

 Florida. In the Eecent it ranges from Prince Edward Island to the 

 northern shores of South America including the "West Indian Islands. 



Width, 13 mm.; height, 16 mm. 



Occurrence. — Talbot Formation. Wailes Bluff near Cornfield Har- 

 bor, St. Mary's County; Federalsburg, Caroline County. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 and TJ. S. National Museum. 



Crepidula plana Say. 



Plate LI, Figs. 5-8. 



Crepidula plana Say, 1822, Jour. Acad. Nat. Sci. Phila., vol. ii, p. 226. 

 Crepidula plana Dall, 1889, Bull. U. S. Nat. Mus., No. 37, p. 152, pi. xlviii, fig. 



12; pi. 1, fig. 26. 

 Crepidula plana Dall, 1892, Trans. Wagner Free Inst. Sci., vol. iii, pt. ii, p. 



358. 

 Crepidula plana Martin, 1904, Md. Geol. Survey, Miocene, p. 250, pi. lix, 



figs. 5a, 5b. 



Description. — " Shell depressed, fiat, oblong oval, transversely 

 wrinkled, lateral margins abruptly deflected; apex not prominent, and 

 constituting a mere terminal angle, obsolete in the old shells; within 

 white; diaphragm occupying half the length of the shell, convex, con- 

 tracted in the middle and at one side." Say, 1822. 



" Having much confidence that this form will prove to be a dynamic 

 mutation of other resident species, both in the fossil and the recent 

 faunas, I prefer to adopt a name for it which applies strictly to the 

 American form, though the latter cannot be distinguished by the shell 

 from the European unguiformis and analogous individuals found in 

 foreign waters in most parts of the world. The fossils are absolutely 

 identical in all essential characters with the recent specimens.'' Dall, 

 1892. 



This very widespread species is recognized in the Oligocene of Florida 

 and Jamaica, is common in the Miocene from New Jersey to Florida, in 

 the Pliocene of the Carolinas and Florida, in the Pleistocene from Massa- 



