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.847 



TERTIARY FAUNA OF FLORIDA 



Eocene of Carson's Creek, Wahtubbee, Meridian, and Heidelberg, Mis- 

 sissippi ; Vicksburgian of Vicksburg and Red Bluff, Mississippi. 



Cortaula engonata var. Burnsii Dnll. 



Upper Oligocene of the Chipolu beds, on the Chipola River and at 

 Ballast Point, Tampa Bay, and in the lowerbed at Alum Bluff, Chattahoochee 

 River, Florida ; Burns and Ball. 



This form, doubtless a direct descendant of the earlier one, differs from it 

 in its larger size and more prominently arcuate base. The form and sculpture 

 otherwise is essentially similar. Lon. n, alt. 7, cliam. 6 mm. The measure- 

 ments of the largest C. engonata in the collection are: Ion. 8.5, alt. 5.5, diam. 

 4 mm. 



The Upper or Chipolan Oligocene is either better explored or more pro- 

 lific in forms of this family. 



Corbula (Cuneocorbula) sphenia n. s. 



1'l.ATE 36, KlGURK IO. 



Chipola beds, at the typical locality on the Chipola River, Florida; Burns. 



Shell solid, somewhat inequivalve, the posterior ventral margin of the 

 right valve folded in ; beaks moderately prominent, somewhat anterior ; 

 anterior end of shell evenly rounded, base somewhat prominent under the 

 beaks, posterior end sharply pointed with a well-marked keel on the rostrum ; 

 surface showing (about eighteen) narrow concentric ribs, with the steeper 

 slope upward, and somewhat wider interspaces, feebler on the beaks and 

 similar on both valves; there is no radial sculpture, the cardinal tooth is 

 strong, and in the left valve behind the socket there is a small tubercle on the 

 margin of the valve. Lon. 17, alt. 10, diam. 7.5 mm. 



This species recalls C. (^Cuneocorbula) dominiccnsis Gabb (Geol. St. Do- 

 mingo, p. 247, 1873), which is a larger shell, from the Oligocene of St. 

 Domingo. 



Corbula (Cuneocorbula) sarda n. s. 



1'l.ATK j(J, FlliCRK 14. . 



Chipola Oligocene of the lower bed at Alum Bluff, Chattahoochee River, 

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

 Burns. 



Shell stibequilateral, thin, slender, inequivalve, the right valve higher and 

 less strongly sculptured ; anterior end rounded; base arcuate, prominently so 

 in the right valve; posterior end obliquely and narrowly truncate, with two 



