99 St. Maurick and Claiborne PkIvEcypoda 99 



is of an adult. Compared with trapaqiiara, a?itestriata is much 

 more oblique, or inequilateral, the posterior extremity is sub- 

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

 vex. Externally antestriata is more strongly marked' ' . 



7>^^.— Coll. Phila. Acad. From IvCe Co., Tex. 



Horizon. — St. Maurice Eocene. 



Specimen figured. — Singley's collection, Lee Co., Tex. 



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

 ing, Ivce Co. ; Alabama Bluff, Trinity River ; 5 miles W. of 

 Crockett ; Hurricane Bayou ; Baptizing Creek, Cherokee Co. 



CrassateSHtes rhomboideus Conrad, PI. 34- Fig- 4- 



Crassatella rkoniboidea 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 ('not of d'Archiac, 1840^" 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 tj^pe 

 with its beautifullj^ undulating exterior flourished everywhere. 

 In the St. Maurice of the Gulf States the protexta-\C&& 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 



