99 St. Maurice and Claiborne Pelecypoda 99 



is of an adult. Compared with trapaqiiara, antestriata is much 

 more obHque, or inequilateral, the posterior extremit}' is sub- 

 biangular and crenate within, and the basal margin is more con- 

 \'ex. Externally antestriata is more strongly marked". 



Type.—^oW. Phila. Acad. From Lee Co., Tex. 



Horizon, — St. Maurice Eocene. 



Specimen figured. — Single}'' s collection, Lee Co., Tex. 



Locality. — Elm Creek, between Evergreen and Orrell's cross- 

 ing, Lee Co. ; Alabama Bluff, Trinity River ; 5 miles \V. of 

 Crockett ; Hurricane Bayou ; Baptizing Creek, Cherokee Co. 



Crassatellites rhomboideus Conrad, PI. 34. Fig. 4. 



Crassatella rhonboidea Con., Am. Jr. Sci., vol. i, 1846, p. 396, pi. 3, 



fig- 5- 



Oblong, rhomboidal ; anterior margin obliquely subtruncated at base ; 



posterior margin obliquely and widely truncated, the inferior extremity 



rounded ; posterior dorsal margin not very' oblique ; basal margin slightly 



curved. 



Orangeburg, S. C. 



Dall refers (Trans. Wag. Ill, p. 1469) to "C. rhomboideus 

 Conrad, 1865 fnot of d'Archiac, 1840J" as being an "ill-defined 

 or doubtful Eocene" form. 



We do not understand why Dall gives this late date for Con- 

 rad's species but quite agree with him in considering it a doubt- 

 ful form. From its general shape we strongly suspect Conrad 

 had a Miocene cast in hand when describing this "species". 



Crassatellites protexta stock 



This long type of Crassatellites is particularly characteristic 

 of the upper half of the Eocene of the Gulf States. In the Vir- 

 ginia basin, during the Sabine age, the drawn-out alceformis t3'pe 

 with its beautifully undulating exterior flourished everjrwhere. 

 In the St. Maurice of the Gulf States the protextaASk& forms ap- 

 peared abundantly to the east of the Mississippi ; only rarely, so 

 far west as the Rio Grande. In the Claibornian at Claiborne it 

 appears to us that a representative of the most primitive form of 

 this stock is preserved. From some form like this it would seem 



