64 BuLivETiN 4 178 



or behind the sinus anterior to the umboual ridge, the folds dis- 

 appear and the shell is smooth. 



The lower or basal portion of the valve is also smooth. Other 

 specimens are covered with much finer folds to the basal margin, 

 while on others the markings are nearly obsolete. 



One internal feature of this species is worthy of note, viz., the 

 extreme obliquity of the cartilage pit (see figures). This is 

 practically the same as seen in C. alceformis. The last mentioned 

 -species, however, differs considerably from C. gabbi. Its umbones 

 are flat, its lirations broader, and the length of the shell is far 

 greater. 



Localities. — Texas: Brazos river, at Cretaceous-Eocene contact; 

 Brazos river, Milam-Falls Co. line (see pi. 5, fig. 

 10, 11); Rocky Cedar creek, public road crossing, 

 Kaufman Co. ; Briar creek, northern part of Gibb's 

 survey, northern, Milam Co.; near Webberville, 

 Travis Co. 



Arkansas: N. W. of S. E. }i, Sect. 8, i S., 13 

 W., and half a mile S.; Sect. 36, i S., 16 W. 



Tennessee: Type specimen, 2 mi. S. of Middleton 

 (pi. 5, fig. 7, a.); others 2 mi. E. of Middleton; 

 Hannah's, i^ mi. N. B. of Crainesville, Harde- 

 man Co., bed b\ y2, mi. W. of Hannah's; Hud- 

 dleston's, 3 mi. W. of Crainesville; McDonald's 

 mill, 4 mi. S. W. of Middleton. 



Mississippi: Reeves, 2}^ mi. N. W. of Walnut. 



Alabama: ? ^ mi. W. of Prairie Bluff, bed e 

 (casts only); j^ mi. N. W. of Prairie Bluff, old 

 field; ly^ mi. S. W. of Palmer's mill, at S. Mc- 

 Connico's; roadside, i mi. S. of Palmer's mill 

 (pi. 5, fig. 8); ly-i mi. N. E. of Clayton. 



Georgia: The station mentioned in my Arkansas 

 Report, vol. ii, p. 43, as 3 mi. below the mouth 

 < of Pataula creek, is probably on the Georgia side 

 of the Chattahoochee. 



Crassatella sepulcollis Vi.. sp., PI. 6, fig. i. 



Specific characterization. — Size and general form as indicated 

 b}^ the figure; beaks, anterior, prominent, curving anteriorly; 

 young shell nearly quadrangular and strongly marked with dis- 

 tant rugae; becoming elongate and smooth with age; lunule deep, 

 well but not sharply defined; escutcheon well defined, extending 

 from beak to a little over two-thirds way to posterior-dorsal 

 angle; post-umbonal slope broad; cartilage pit small, extending 



