8x St. Maurice and Claibokne Pelecypoda 



ant of the Woods Bluff form and the progenator of rottinda, carson- 

 ends &c. Wautubbee and Johnson's Place, Miss. 



Venericardia (rotunda ?) var. coloradonis, PI. 29. Fig. 9. 



A form occurring at Smithville, Tex., z.vcLOVi.% flabellum, de- 

 cidedly inflated centrally, having a wilcoxensis-X-ik& appearance, 

 with ribs laterally terraced and crenules somewhat cup-shaped 

 but comparatively far apart. Also found on the Sabine, La. 

 side 200 yds below the mouth of Bayou Negreet. 



Venericardia trapaquara Harris, PI. 30. Figs. 6-9. 



V. trapaquara Harris, Proc. "^hila. Acad. Nat. Sci. 1895, p. 48, pi. i, 

 fig. 7- 



Harris's original description. — General form as figured ; ribs about 

 Iwenty-four, compound, i. e., broad at base, surmounted by a medial dentate 

 carina ; umbonal ridge prominent. 



This species is remarkable for its quadrangular form and the promi- 

 nence of the umbonal ridge. It belongs to the alticostata stock and is most near- 

 ly allied to Cardita subquadrata Con. (Jr. Acad. Nat. Sci. Phila. 2d Ser.,1848, 

 p; 128, pi. 14, fig. 10), but from Conrad's description and figure it is evident 

 that his species is much more compressed, the umbonal region less prom- 

 inent, and the beaks more nearly central. 



Locality. — Cedar Creek, southwest corner of Wheelock L,eague, 200 

 yds. north of Brazos Co, line, Robertson Co., Tex. 



Geological horizon. — Ivower Claiborne Eocene. 



Type. — Texas State Museum. ' 



A photograph of the specimen described over twent}^ 5^ears 

 ago is given herewith, fig. 8. It is considerably eroded and the 

 true character of the surface markings scarcely determinable from 

 the type. From other localities, for example Clear Lake, La. , 

 specimens of the same quadrate form with short ligamental mar- 

 gin appear with others like those shown in figs. 6 and 7, pi. 30. 

 It is clear from occasional well-ornamented specimens that the 

 ribbing though usually showing terracing but faintly, may show 

 it distinctly in places with the crenulation approaching that of 

 the Sabine ''alticostata". The shell, however, is not so in- 

 flated as in that species, and the generally well-defined umbonal 

 ridge and the postero-basal angle give the shell a very different 

 appearance from the somewhat VerticordiaASk& Sabine form. 



