15 American Tertiary Shells 15 



basally and posteriori}'. 



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 posteriori}', fine concentric 

 lining. These lines are almost rectilinear medialh' but curve U]:) 

 rather abruptly anteriorl}' and posteriorly. 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 generalh' ornamented by 

 highh' raised, scale-like or imbricating concentric lines ; costation 

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

 tern, especiall}- in the left valve ; central rib largest of the three 

 or five major ones. 



The general appearance of this shell is so different from an\-- 

 thlng 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 specimens figured. — Deposited by G. D. Harris in 

 Museum at Cornell Univ. 



Locality. — Found in light, marl}- 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.? PL 2. Figs. 10, ir. 



A few fragments of another species of Pecten were found 



