BuivIvBTIN 31 12 



eastward through Wautubbee and Hickor}^ Miss., Claiborne, 

 Coffeeville and Lisbon, Ala. ; Shell Bluff, Ga. ; Vance's Ferr3^ 

 S. C. ; City Point and Piping Tree, Va., these heav^'weights 

 are of common occurrence. 



Young, comparativel}' thin specimens of this type have a 

 wide distribution in the St. Maurice beds of Texas, and are 

 not uncommon eastward to the Carolinas. In these the posterior 

 kink is not alwa3's well defined and now and then there is a slight 

 trace of radial sculjDture on the flat valve. (See pi. 6.) 



Var. divaricata Lea simply represents 5-oung individuals with- 

 out a definite posterior kink and without a posterior cardinal ala- 

 tion. Such specimens are occasionally found with other varieties 

 at Claiborne, Ala., Negreet, La., and elsewhere. (See pi. 9, 

 fig. 7. Dall mentioned also Natchitoches Pari.sh, La., Choctaw 

 Bluff, Ala. , and City Point, James River, Va. 



Var. vermilla de Greg. Like divaricata but with posterior 

 alation of cardinal area. Described from Claiborne ; our best 

 specimens from Bienville Par., La. (See pi. 9, fig. 8.) 



Type. — Phila. Acad. ; from the lower calcereous laj^ers, 

 Claiborne Bluff, Ala. 



Horizon. — St. Maurice and Claiborne Eocene. 



Specimens figitred. — PI. 6, figs. 2-12, young specimens from 

 the base of the bluff at Claiborne ; pl. 7, adult from the same lo- 

 cality ; pl. 8, var. smithvillensis , C. U. Museum, from Smith- 

 ville, Tex, ; pl. 9, fig. 7, var. divaricata, C. U. Mus., from New- 

 ton, Miss. ; pl. 9, fig, 8, var. vermilla, C. U. Mus., Beinville Par- 

 ish, La. 



Ostrea seMaeformis (?) var. lisbonensis, Pl. 9. Figs 1-6 



We have never felt satisfied with the general reference of 

 this form to sellcBformis and have long kept it apart from Conrad's 

 species in our collections under the designation of lisbonensis. It 

 occurs large and well defined at Lisbon, Ala., but it is in Louisi- 

 ana where it is typically and extensivel}^ developed. When adult, 

 it reaches about one-half the dimensions of the large sellceformis 

 in the bluff at Claiborne. The coarse plications, aviculoid form, 



