133 ^T. Maurice and Claiborne Pelbcypoda 133 



One instinctively thinks of C. magnum while looking upon 

 this specimen, but viagnu7n has many more ribs, is more oblique 

 and has less extended, less prosogyrate beaks. 



Type. — Deposited in Paleont. Lab., C. U. 



Horizon. — St. Maurice Eocene. 



Locality. — Vicinity of Long Point, Y^ mile below Alabama 

 Landing, west side of the Ouachita River, La. 



Protocardia gambrina Gabb, PI. 42. Figs. 2, 3. 



".^ /'. diversa"' Gabb, Proc. Acad. Nat. Sci. , Phila. , 1861, p. 370. 



P. gambrina Gabb, idem, p. 371. 



P. harrisi Dall, at least in part, Trans. Wag., Ill, 1900, p. 11 13. 



Regarding this species Gabb remarks : "/*. diversa Coji. sp. 

 — A small specimen from Hou.ston Co. , Texas, from an Eocene 

 deposit presenting most of the characters of this species, but 

 differs in some few points. It has the form of the typical speci- 

 mens of P. diversa except that the buccal extremity is more reg- 

 ular, the basal margin is entire, and not sinuous as in adult 

 specimens of that species ; this may be however merely the ef- 

 fect of the difference in age. The anterior portion is marked by 

 obsolete cancellations, and the posterior radiations are somewhat 

 different. The ribs are broad and rounded, with small bars 

 placed at short interv^als connecting them, while in the young 

 state of P. diversa the ribs are linear with wide spaces and with- 

 out connecting bars. In that species, also, the radiating portion 

 of the surface blends into the adjoining surface by the ribs be- 

 coming obsolete, while in this specimen the same portion ends 

 abruptly, the ribs all being of the same size. It will be necessary 

 to examine more specimens to decide whether this is the young 

 of the above species or distinct. Should it prove so, I suggest 

 the name P. gambrina.'' 



Dall remarks regarding this form : "/*. gambrina Gabb, 

 from the Oligocene of Texas, is the young of P. diversa, as Gabb 

 suspected." (Trans. Wag. , III, p. 11 14.) 



Dall seems to have overlooked the fact that this is an Eocene 



