TRANSACTIONS OF WAGNER 

 662 



TERTIARY FAUNA OF FLORIDA 



can be given of several of the following species, though their distinctness 

 appears beyond doubt. 



Atrina jacksoniana n. s. 

 Lesueur, Walnut Hills Fossils, pi. 5, fig. 5, 1829. 



In the Jacksonian Eocene of Green's marl bed, at Jackson, Mississippi, 

 and Garland's Creek, near Shubuta, Clarke County, Mississippi, Burns; and 

 at Creole Bluff, Grant Parish, Louisiana, Vaughan and L. C. Johnson. 



Shell thin, fragile, rapidly widening, somewhat compressed along the 

 ventral border ; sculpture of near the beaks numerous feeble, more or less 

 wavy, longitudinal elevated lines, which become less distinct vcntrally, and 

 are obsolete over the greater portion of the shell, which appears from the 

 numerous fragments to have been nearly smooth posteriorly, or with a few 

 feeble concentric wavelets, most prominent vcntrally. A fragment (including 

 the beaks), forty-five millimetres long, has a dorso-ventral maximum diameter 

 of thirty-four, and a transverse diameter of about twenty millimetres. The 

 valves are evenly arched, and become more convex behind. 



The material is abundant but very fragmentary, yet sufficient to establish 

 the identity of the species at these localities and its distinctness from the 

 others mentioned. 



Atrina argentea Conrad. 



rin/iii argciilca Conr., Proc. Acad. Nat. Sci. 1'hila., iii., pp. 295-6, 1848; Journ. A< ,ul. 

 Nat. Sci., 2d Ser., i., p. 126, pi. 13, fig. 31, 1848. 



Vicksburgian Oligocene of Vicksburg, Mississippi, where it is abundant 

 in the form of impressions in a brownish clay ; Conrad and Worthen. 



It is quite certain from the appearance of the casts that the surface of the 

 valves originally possessed a certain number of small, feeble, spinose pro- 

 cesses along the principal radial ribs. The specimens examined average 

 about eighty millimetres in length. 



Atrina (argentea var. ?) chipolana n. s. ? 



Upper Oligocene of the Chipola marl, Calhoun County, and of the Oak 

 Grove sands, Santa Rosa County, Florida; Burns. 



This form is only represented by fragments. It would appear to attain 

 about the size of A. argentea, but to be somewhat more convex and arcuate. 

 The chief distinction is in the sculpture; the dorsal areas of the valves of both 

 have about five equidistant radial riblets ; the ventral areas in argentea have 



