TRANSACTIONS OF WAGNER 

 678 



TERTIARY FAUNA OF FLORIDA 



Variety divaricata Lea, Choctaw Bluff, Alabama; Natchitoches Parish, 

 Louisiana ; City Point, James River, Virginia. 



Variety perplicata Dall. 



Eocene, Caton's Bluff, Conecuh River, Alabama ; L. C. Johnson. 



Shell very heavy, arcuate triangular, with coarse, rounded, numerous 

 divaricating ribs (twenty-five to forty), no auriculation or posterior sinuosity 

 of the margin near the hinge, the upper valve extraordinarily ponderous, the 

 general form regular and uniform, the valve margins nearly or quite simple. 



Variety nigifera Dall. 



Middle Oligocene of the Chipola beds at Alum Bluff and on the Chipola 

 River, Florida, and in the silex beds at Ballast Point, Tampa Bay, Florida ; Dall 

 and Burns. 



Shell rather thin, irregular, coarsely ribbed, more or less imbricated, 

 margin plicate, form tending to ovate or rounded. 



The above varieties belong to the section Cymbulosirea of Sacco. 



Variety pauciplicata Dall. 



Upper Oligocene of the Oak Grove Sands, Santa Rosa County, Florida ; 

 Burns. 



Shell fan-shaped with acute beaks, thin, with few (seven to fifteen) rather 

 large, loosely imbricated radial but not divaricating ribs, the scales more or 

 less fluted, thin, and elevated ; upper valve falcate, with concentric lamina? ; 

 structure flattish and thin. 



This seems remarkably distinct from the others and points towards such 

 species as subfalcata Conrad; but the whole series seems to be a continuous 

 development from the Lower Eocene divaricata to the present form. The 

 typical stllceformis appears to be a merely local development, probably from 

 some peculiarity of situs of the individuals concerned. It was some time 

 before I could bring myself to unite some of the very distinct looking forms 

 which have been called divaricata with the selUzformis type, but careful study 

 of a large series has convinced me that this is the proper course. It would seem 

 as if there must be some especial reason for the singularly massive and regu- 

 lar character of the variety perplicata, but occasional specimens of divaricata, 

 verging on typical scllceformis, exhibit a similar thickening. Gregorio adds 

 a variety vermilla and another variety Iceta for modifications of sculpture. 



Ostrea alabamiensis Lea. 



O. alabamiensis Lea, Contr. Geol., p. 91, pi. 3, fig. 71, 1833. 

 O. linguacanis Lea, op. cit., p. 92, pi. 3, fij, r . 72, 1833. 



