171 Midway Stage 57 



doubtless all belong to one species. This is one of the typical 

 Midway forms, occurring quite abundantly throughout the same 

 areal extent and horizons with Encliniatoceras ^drichi. 



Localities. — Texas: Brazos river, from Cretaceous-Eocene con- 

 tact to Falls-Milam Co. line, several localities. 



Arkansas: Marshall's well, Capitol Hill, I^ittle 

 Rock; Sect. 2, 3 S., 16 W.; Sect. 18, 2 S., 15 W. 



Tennessee: Hannah's, i^ mi. N. E. of Craines- 

 ville, Hardeman Co., beds a &/; Huddleston's, 2 

 mi. W. of Crainesville. 



Mississippi: Blue Mt., S. of Ripley. 



Alabama: Black Bluff; Tombigbee river, 4 mi. be- 

 low Black Bluff; hill just N. of Prairie Bluff; 

 Matthews' Landing; }4, mi. W. of Graveyard hill; 

 I mi. W. of Oak Hill; Palmer's mill; Bed e, yi 

 mi. W. of Prairie Bluff; Dale's branch; " Encli- 

 matoceras limestone' ' at Hamburg. 



VENERICARDIA. 



Venericardia alticostata, PI. 4, fig. 12. 



Syn. V. alticostata Con., Amer. Jr. Sci., vol. xxiii, 1833, p. 342. 

 V. perantiqua Con., Amer. Jr. Conch., vol. i, p. 8. 

 V. perantiqua Whitf. , Mon. U. S. G. S., vol. ix, p. 232, 

 pi. 30, figs. 8-10. 



Conrad' s original description. — "Shell subcordate, convex, with 

 about twenty-two profoundly elevated nodulous ribs, which on 

 the anterior side are laterally carinated. Length, two inches. 



''Locality. — Claiborne, Ala. London clay. Extremely abun- 

 dant and very variable in outline." 



The first forms that presumably merge into this species are 

 very small, about i centimeter in length, with 12 ribs, and occur 

 at the very base of the Midway, 3^ mi. N. E. of Snow Hill 

 and in the vicinit}^ of Prairie Bluff. See base of off-set in section 

 (p. 31). Higher up in beds of this off-set a form more nearly 

 typical is encountered. It has from 14 to 18 ribs and is an inch 

 or more in length. 



Localities. — TexAS: 18 mi. S. E. of Eagle Pass. — Dr. White; 

 near Webberville. 

 Alabama: Snow Hill, R. R. cut; i>^ mi. N. of 

 Snow Hill, R. R. cut; 2 mi. N. of Snow Hill, R. 

 R. cut; Palmer's mill. 



Closely allied forms occur at the base of the Midway on the 



