PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 73 



potholes 8 to 10 feet in diameter had been eroded in the underlying shale and 

 the fossil-bearing blue clays laid down in them. At other places the fos- 

 siliferous beds seem broken and piled together in every direction. The entire 

 fossil-bearing area is not more than 200 feet in length, and a few hundred 

 yards below this the main body of shales ends abruptly as though faulted, 

 and the water plunges into a deep pool. 



The material in which the fossils occur is very similar to that of the main 

 body of the shales, but the fossils here are entirely confined to the disturbed 

 and eroded area, and not a single fossil was found elsewhere in this exposure, 

 and none at all was found in the main body of shale. 



The fossUs are fragile and, while abundant in this limited locality, are hard 

 to separate from the shale. 



The fossils from the Alazan shales were submitted to Dr. R. E. Dickerson, 

 .who reports that they are of upper Eocene age, containing some forms char- 

 acteristic of the Tejon of California and others of the upper Eocene of the 

 Gulf coast. 



Although the Alazan clay has heretofore been correlated with 

 upper Eocene deposits, study of the fossil mollusks has convinced the 

 writer that the beds from which they came are of Vicksburg (Oligo- 

 cene) age.^ As the overlying Meson formation has been correlated 

 with the Glendon formation, the Alazan doubtless is equivalent to 

 the Mint Spring marl member of the Marianna limestone. No char- 

 acteristic Eocene species were recognized. The species in the fol- 

 lowing list are common to the Alazan clay and the Vicksburg group 

 of Mississippi : 



Oenimula rotaedens (Conrad) 

 Pleuroliria cochlear is (Conrad)? 

 Pleurofusia afC. P. servata (Conrad) 

 Drillia tantula (Conrad) 

 Drillia cf. D. caseyi Aldrich 

 Latirus protractus (Coni'ad) ? 

 Latirus perexilis (Conrad) 

 Distorsio crassidens Conrad 

 Phos nvississippiensis (Conrad) 

 Turritella mississippiensis Conrad 



Polynices (Euspira) byramensis Cooke 

 Sinum nUssissippiense Conrad 

 AroMtectOnica trilirata vicksburgensia 



(Ball) 

 Cassis caelatura Conrad var.? 

 Pecten pouUoni Morton? 

 MacrocalUsta ( Chionella) s obr ina 



(Conrad) ^ 



Corbula laqueata Casey 

 Corhula engonata Conrad 



The following species are described as new in this paper : 



Turritella ceibana Cooke 



Natica alazana Cooke 



Polynices (Lunatia) laorimans Cooke 



Polynices (Euspira) byramensis CookjB 



AmpulUiia vaughani Cooke 



Dentalium ovale Cooke 



Gemmula alazana Cooke 

 Gemtnula mewa Cooke 

 Gemmula msxa var. mexita Cooke 

 PseudotomM, alazana Cooke 

 Scobinella prionota Cooke 

 Glyptotoma rhombica Cooke 

 Borsonia aguilae Cooke 

 Ancilla (Ancillina) alazana Cooke 

 Protonema bartschi Cooke 



Dentalium alazanum Cooke 

 Amussium alazanum Cooke 

 Pecten ceibanus Cooke 



The species named in the preceding lists probably include only a 

 small part of the total number of mollusks in the Alazan claj. Al- 



* This correlation was announced Dec. 27, 1923 ; see Geol. Soc. Amer. Bull., vol. 35, 

 pp. 853, 856, 1924. 



