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1067 



TERTIARY FAUNA OF FLORIDA 



Yorktown on the York River, and at Williamsburg, Virginia ; also at Mur- 

 freesboro, Hartford County, North Carolina, according to Conrad. 



This species was confounded with the Venus rustica of Sowerb}', a British 

 Crag fossil belonging to the genus Cyprina of Lamarck {^ Arctica Schum.), 

 and Orbigny, on the ground that they were not identical, and probably over- 

 looking Say's previous description, renamed the shell /. Conradi. This of 

 course is not identical with the Isocardia Conradi Gabb (Journ. Acad. Nat. 

 Sci., 2d Ser., iv., p. 392, pi. 68, figs. 21, 21a, i860) from the Cretaceous marl 

 of Timber Creek, New Jersey (described and figured also by Whitfield, Mon. 

 U. S. Geol. Surv., ix., p. 200, pi. 25, figs. 3, 4, 1885) and Prairie Bluff, Alabama. 

 The Cretaceous species may take the name of Isocardia Gabbi, since the 

 present name is untenable. 



The /. fraterna seems to have but a limited distribution in the Miocene. 

 The young are rather more elongated than the adult proportionately and 

 senile specimens again become drawn out so that the outline of the shell, 

 as well as the undulation of its surface, are exceedingly variable. The stria- 

 tion of the lateral tooth, mentioned by Conrad, is not a constant feature, as 

 this tooth is often smooth. Nevertheless, it is quite a characteristic shell. 

 An internal cast, probably of this species, was collected in the Miocene clays 

 of Chilmark, Martha's Vineyard, Massachusetts, by J. B. Woodworth. 



This species has been united with the Isocardia humana of Europe by 

 Deshayes, Hoernes, and others, but this appears to me quite inadmissible. 



Isocardia Markoei Conrad. 

 Isocardia Markoei Conrad, Bull. Nat. Inst., ii., p. 193, pi. 2, fig. i, 1842. 

 Glossus Markoei Conrad, Proc. Acad. Nat. Sci. Phila., vii., p. 29, 1854; Meek, Mioc. 



Checkl., p. 8, 1864. 

 Bucardia Markoei Conrad, Proc. Acad. Nat. Sci. Phila. for 1862, p. 576, 1863. 



Miocene of Calvert Clifl^s, Maryland, Markoe, Foreman, and O'Brien; 

 Plum Point, Maryland, Burns (upper bed). 



This well-characterized and compact species has not been, so far as I have 

 heard, discovered anywhere outside of Maryland. 



Isocardia Carolina n. sp. 

 Plate 46, Figure 22. 

 Miocene of Edgecombe County, North Carolina, J. E. Bridges ; Grove 

 Wharf, James River, Virginia, Burns. 



Shell large, solid, rotund, rather thin for its size, with involute beaks, 



