247 LiGNiTic Stage 55 



Form /?. A large somewhat triangular variety of 28 or 30 

 costae, with a tendency to become nasute posteriorly. These fea- 

 tures are shown to some extent in pi. 9, fig. i. It will be ob- 

 served that on the greater portion of the surface the ribs are far 

 wider than their interspaces. In the center of each rib there is 

 often a trace of an interrupted, raised, radiating line. Hinge, 

 powerful. Typical localities, Gregg's landing. Bell's landing, 

 occasionally at Yellow bluff. 



Form y. A large heart-shaped variety of about 20-22 ribs, 

 distincfl near the umbo, but quickly becoming reduced to very 

 faint undulations on a comparatively smooth surface. This form 

 is shown by figs. 1-4, pi. 10. It is fairly abundant at Woods bluff 

 and Ozark, and in the Lower Claiborne at Lisbon. Specimens 

 from I %, miles w. s. w. of Choctaw corner, combine the outline 

 of ^. with the surface of y. 



Form 6. This is the form found in such great profusion at 

 Hatchetigbee bluff. Of all American specimens this seems most 

 nearly related to the V. planicosta of Bracklesham bay and the 

 Calcaire grossier In general. A specimen from Woods bluff 

 showing most of the features of this form is shown on plate ro, 

 fig. 5. The ribs, about 30 in number, are obsolescent on the lower 

 moiety of the shell. There is here a tendency to show a slight 

 straightening or truncation of the anterior sub-margin, a feature 

 so noticeable in specimens from the Calcaire grossier horizon of 

 Europe, and one that generally serves to distinguish at once for- 

 eign from American specimens. A small specimen of this variety 

 has been described and figured by Conrad under the name of 

 Cardita densata, Jour. Acad. Nat. Sci. Phila., vol. i, pi. 14, 

 fig. 24. 



Lignitic localities. — Alabama : Nanafalia; Tuscahoma; Woods 

 Bluff; i^ miles w. s. w. of Choctaw Corner; Yel- 

 low Bluff; Gregg's and Bell-'s Landings, four miles 

 above Hamilton Bluff; Ozark. Georgia : Ft. 

 Gaines. 



Specimens figured. — PI. 9, fig. i, Bell's Landing; Harris col- 

 ledlion. Fig. 2 and fig. 3, Woods Bluff, C. U. colledlion ; p. 130, 

 pi. 10, Woods Bluff, Paleont. Museum, Cornell Universit3^ 



Venericardia alticostata, var. Pl. n^ fig. i. 



Syn. See Bull. Amer. Paleont., vol. i, p. 171, 1896; add: — 



Cardita decusata Tuomey, 2d Biennial Rep't, p. 271, 1858. 



