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683 



TERTIARY FAUNA OF FLORIDA 



Upper Eocene of the west bank of the Suwanee River, near the Sulphur 

 Spring, Florida; Eldridge. 



This singular species differs from 0. pcrcrassa and heavy specimens of 

 (). trigonalis in its few strong plications and the rounded lateral portions of 

 the hinge-area, which in the above-mentioned species are conspicuously flat. 



Ostrea percrassa Conrad. 



<>. fit'fi'nis.tii Conr., Fos. Mcd. Tert., p. 50, pi. 25, fig. I, 1840; I'roc. Acad. Nat. Sci. 

 1'hihi., xiv., ]>. 582. 



? Eocene of Wood's Bluff, Alabama, and near Lawrence, Mississippi; L. 

 C. Johnson (var. syhi&rupis Harr.). 



Miocene of Stow Creek, Cumberland County, New Jersey, Conrad; of 

 Shiloh and Jericho, New Jersey, Burns ; of Magnesia Spring, Alachua County, 

 Florida, Burns. 



This species in its typical form is of a porous and vesicular texture, giving 

 the extremely thick shell a surprisingly light weight. 



Specimens from the southern Eocene cited above have the same form 

 and characteristics, but the usual dense and heavy shell of other oysters. 

 These latter might be taken for exceptionally thick and senile specimens of 

 O. trigonalis, which in that case would figure as the original stock of 0. 

 percrassa. 



This completes the list of positively Eocene species ; the 0. panzana 

 Conrad (P. R. R. Rep., vii., pt. I, p. 193, pi. 2, fig. 4, 1857 + 0. pansa Conr. 

 (err. typ.), 1 866), which was doubtfully referred to the Eocene by Conrad, is 

 a perfectly unidentifiable species described from a worn and extremely obscure 

 type now in the National Collection, but which probably belongs to a horizon 

 later than the Eocene. 



Ostrea georgiana Conrad. 

 (>. i;'i't>ri;'ia>iii Conr., Journ. Arad. Nat. Sci. I'liila., 1st Scr., vii., p. 156, 1834 ; Dana, Man. 



Ociil., 1st ed., p. 519, fig. 811, 1863. 



O. <-(>tilr<it ta Conr., Rep. Mex. Hound., vol. i., pt. ii., p. 160, pi. 18, fig. I, 1857. 

 (>. titan Conr., I'roc. Arad. Nat. Sci. 1'hila., vi., p. 199, icS,4 ; I'ac ific R. R. Rep., vi., 

 p. 72, pi. i\., fig. 17 a, pi. v., fig. 17 a, 1857. 



Oligocene of the lower bed at Vicksburg, Mississippi, and Choctaw Bluff 

 on the Alabama River, Alabama ; also at Clarksville, Alabama, and Shell 

 Bluff, Savannah River, Georgia; Miocene of Oyster Point, upper Rio Grande, 

 near Roma, Mexico; Martinez, California; Roberts Ferry, near New Berne, 

 North Carolina. 



