15 



American Tertiary Shells 



15 



basally and posteriorly. 



Small casts of these species are common at Wilmington and 

 Eutaw Springs. Sometimes at the former locality specimens the 

 size of fig. 5 are found. An impression of the exterior of what 

 appears to be the same species is in our collections, labelled Neuse 

 River, 16-17 miles above Newbern, N. C. This shows, besides 

 rather regular concentric undulations posteriorly, fine concentric 

 lining. These lines are almost rectilinear medially but curve up 

 rather abruptly anteriorly and posteriori y. This reminds one of 

 Ball's M. agassizi, a recent West Indian species. 



Types. — Paleont. Museum, Cornell Univ. 



Localities. — Eutaw Springs, S. C. ; Wilmington, N. C, and 

 Neuse River above Newbern. 



Pecten trentensis. n. sp., PI. 2. Figs. 8, 9. 



Specific characterization . — Form and size as indicated by the 

 illustrations ; ribs highly variable in number, size and amount of 

 ornamentation ; generally bifid and generally ornamented by 

 highly raised, scale-like or imbricating concentric lines ; costation 

 showing a strong tendency towards a tri-or quinque-costate pat- 

 tern, especially in the left valve ; central rib largest of the three 

 or five major ones. 



The general appearance of this shell is so different from any- 

 thing we have heretofore found in the Eocene of this part of the 

 United States that, owing to a lack of well-known species from 

 the same locality, its horizon must at present be considered as 

 doubtful. 



Type and specime7is figured. — Deposited by G. D. Harris in 

 Museum at Cornell Univ. 



Locality. — Found in light, marly bed, right bank of Trent 

 river, near the water's edge, about six miles below Polloksville, 

 North Carolina, in the so-called Trent formation, The latter 

 has been referred to the upper Claiborne or Jackson Eocene. 



Pecten elixatus Con.? PI. 2. Figs. 10, ir. 



A few fragments of another species of Pecten were found 



