Bui^LETIN 31 12 



eastward through Wautubbee and Hickory, Miss., Claiborne, 

 Coffeeville and Lisbon, Ala. ; Shell Bluff, Ga. ; \'ance's Ferr\-. 

 S. C. ; City Point and Piping Tree, Va., these heavyweights 

 are of common occurrence. 



Young, comparativeh' 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 always well defined and now^ and then there is a slight 

 trace of radial sculpture on the flat valve. (vSee pi. 6.) 



Var. divaricata Lea simpl}' represents young individuals with- 

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

 tiou. Such specimens are occasionally found with other varieties 

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

 fig. 7. Dall mentioned also Natchitoches Parish, La., Choctaw 

 Bluff, xVla., and City Point, James River, \^a. 



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 layers, 

 Claiborne Bluff, Ala. 



Horizon. — St. Maurice and Claiborne Eocene. 



Specimens figured. — PI. 6, figs. 2-12, 3'oung specimens from 

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

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

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

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

 ish, La. 



Ostrea sellaeformis (?) var. lisbonensis, PI. 9. Figs 1-6 



We have never felt satisfied with the general reference of 

 this form to sellce/ormis 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 t3'pically and extensivel)' developed. When adult, 

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

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



