128 Bulletin 31 128 



Mysia asfartiforniis Con., Amer. Jour. Conch., vol. i, 1865, p. 147, pi. 



II, fig. 15. 

 Mysia deltoidea Con., Amer. Jr. Conch., vol. i, 1S65, p. 147, pi. 11, 



fig. 10. 

 Diplodonta ungxdina Dall, Trans. Wag., Ill, 1900, p. 1181. 



Conrad's original description. — Shell slightly elevated, or obovate, a 

 little convex, with fine concentric sulci, becoming obsolete with age ; 

 beaks inclining a little forward and the apex acute ; inner margin entire : 

 lunule none. Ivcngth half an inch. (Claiborne, Ala. ) 



Diplodonta uiaidboroensis Clark and Martin, Geol. Surv. Md., 1901, 

 Eocene, p. 173, pi. 36, fig. 4, ma}- be a variery of this species. 



This is one of the most abundant fossils at Claiborne. It 

 varies considerabl}^ in thickness of the shell, outline and size. 

 Occasionally an almost di.scoid form is seen ; occasional speci- 

 mens twice the usual size are apt to be discoidal and rather thin. 



Type. — ? 



Horizon. — Claiborne and St. Maurice Eocene. 



Specimens figured. — Paleont. Mus. Cornell Univ. 



Localities. — Claiborne and Lisbon, Ala. 



Diplodonta nana Lea, PI. 40. Figs. 15, 16. 



Egeria nana Lea, Cont. to Geol., 1833, p. 55, pi. i, fig. 26. 



E. ? nana Con., Amer. Jr. Conch., vol. i, p. 5, 1865. 



Diplodonta ungnlina de Gr&^., partiin., Mon. Faun. Eoc. Ala., 1890, 



p. 208. 

 Felaniella nana Dall, Trans. Wag., Ill, 1900, p. 1181. 



Lea''s original description. — Shell rotundo-oblique, compressed, 

 angular above, subequilateral, concentrically striate ; substance of the shell 

 rather thin ; beaks pointed, cicatrices imperceptible ; cavity of the shell 

 shallow — of the beak angular ; margin entire. 

 Diam. .1, Length 5-20, Breadth 5-2oths, of an inch. 



Observations. — Closely resembles the I'otunda. It has, however, 

 somewhat larger concentric striae — is a much smaller shell and is more 

 oblique. 



Dall refers this species to Felaniella, a subdivision of Diplo- 

 donta. The same he describes as follows : Shell like Diplodonta, 

 but heavy, compressed, externally smooth, with a conspicuous, 

 usually dark epidermis, and less equilateral valves. 



We herewith figure some small specimens that would be re- 



