82 BUI.I.BTIN 31 8a 



Type. — No 256 in the Texas State Univ., Austin, Tex. Addi- 

 tional specimens figured, pi. 30, figs. 6, 7, 9 in Paleont. Mus. 

 C. U. 



Horizon. — St. Maurice Eocene. 



Localities. — Cedar Cr., Tex. ; Clear I^ake, La. ; Wautubbee, 

 Miss. 



Although the more elongate and quadrangular forms of this 

 species indicate a relationship with alticostata, the more circular 

 approach variations of rotunda. 



Venericardia natchitoches, n. sp., PI. 30. Figs. 10, 13-16. 



Specific characterization. — Size and general appearance as in- 

 dicated by the figures and explanations ; substance of the shell 

 rather thick ; ribs low and broad at base, wider than the inter- 

 spaces, but with a narrow, sharp, serrated median keel, decided- 

 ly a///r^.y^a/a- like, but only 14 or 15 in number ; sub-ligamental 

 ribs not noticeably larger than those on the remaining portion of 

 the shell. A compact, moderate-sized species generall)^ so broken 

 as to appear more elongate than it should, and with carinal ser- 

 ration eroded away. 



Type. — From Natchitoches, La., deposited in Paleont. Mus. 

 Cornell Univ. 



Horizon. — St. Maurice Eocene. 



It would seem quite probable that this is the form from 

 which alticostata was derived, though the number of costae is sur- 

 prisingly small. 



Venericardia alticostata PI. 3°- Figs- i-5v 12, 



For original description, synonymy &c, see these Bulletins, vol. i, p. 

 171 ; vol. 2, p. 247. Other references to closely allied forms or 

 mere varieties of this species may here be added : 



V. blandingi Con., Jr. Phila. Acad. Nat. Sci., vol. 6, '30, p, 229, pi. 



9, fig. 20. 

 ? V. bilineata, ditto, vol. i, '48, p. 128, pi. 14, fig. 9. 

 ? V. subquadrata, ditto, p. 128, pi. 14, fig. 10. 

 V. transversa var. secans de Greg., Mon. Faun. Eoc. Ala., '92, p. 212. 



