TRANSACTIONS OF WAGNER 

 634 



TERTIARY FAUNA OF FLORIDA 



Oligocene of Cumaaa, Venezuela, Guppy ; island in Lake Heniiquillo, 

 St. Domingo, Rowell. 



Shell small, resembling 5. iiicongnia Say in miniature, but with higher, 

 more prominent, and uncompressed beaks, with the ribs of the posterior slope 

 of the right valve smooth instead of nodulose ; the valve higher and shorter, 

 with the beaks more anterior, and the hinge-line somewhat shorter. Lon. of 

 adult shell 26, alt. 25, diam. 21 mm. 



With a rather close general resemblance to A. incongrua Say, this little 

 species differs in details, which, taken in connection with the great disparity 

 in size and the geological horizon, authorize us to regard it as distinct. 



Scapharca (Ounearca) initiator n. s. 

 Plate 32, Figure ii. 



Oligocene of the Chipola beds, Chipola River, Florida ; Burns. 



Shell small, solid, oblique, with prosogyrate beaks, somewhat impressed 

 mesially near the apices of the valves ; right valve ovate-rhombic with twenty 

 strong, rounded, nodulous, radial ribs, separated by wider interspaces ; left 

 valve decidedly smaller, with the ribs smooth, squarish, and without nodules, 

 except a few on some of the shorter anterior ribs ; cardinal area wider in front 

 of the beaks, narrower behind them ; margins of the valves internally fluted ; 

 hinge-line short, with about twenty-two subequal vertical teeth. Lon. (of left 

 valve) 5, alt. 4.7, diam. 5 mm. 



This little shell was at first thought to be the young of a larger species, 

 but nothing allied to it of a larger size has turned up at any locality in the 

 formation, while its solidity gives it a mature appearance. The cardinal area 

 differs in form from any of the known species in the adult state. 



Scapharca (Ounearca) scalaris Conrad. 

 Area scalaris Conr., Proc. Acad. Nat. Sci. Phila., i., p. 324, 1843; Fos. Medial Tert., 

 p. 59, pi. 31, fig. I, 1845 ; Emmons, Geol. N. Car., p. 285, 185S ; Tuomey and 

 Holmes, Pleiocene Fos. S. Car., p. 43, pi. 16, fig. i, 1856. 



Miocene of Petersburg, Virginia, Tuomey; of Duplin County, North 

 Carolina, Burns, and of the upper bed at Alum Bluff, Florida, Dall. 



This species is doubtless the ancestor of 5. scalarina Heilprin, the young 

 of which it much resembles, though sufficiently distinct from the adult. 



Scapharca (Ounearca) scalarina Heilprin. 

 Area scalarina Hp., Trans. Wagner Inst., i., p. 94, pi. 12, fig. 29, 1887. 



