GASTEROPODA OF THE EOCENE MAKLS. 223 



terize the immature shell, or others where the coating has been removed, is 

 distinctly shown. Quite a number of examples have been studied, and no 

 feature appears by which to distinguish it from the typical specimens of the 

 species. 



Formation and locality: In the upper layers of the Upper Green Marls, 

 at Shark River, New Jersey. Collection at Rutgers College. 



CYPR^ID^. 



Genus CYPR^A Linnseus. 



Cypr^a sabulovibidis, n. sp. 



Plate xxxiii, Figs. 20-32. 



Casts of a species of Gyprcea occur in the collection in use, but not 

 numerously. The species has been a small one with but few pronounced 

 features, and of these of course only the general form will be retained on 

 the internal casts. These remains are small, being but little more than 1 

 inch in length; the form is strongly ovate and somewhat "humped" near 

 the anterior end of the dorsal surface; anterior end of the cast distinctly 

 but not largely umbilicated, and the posterior end obtusely pointed and 

 sulcated at the extremity; outer lip somewhat longer than the body of the 

 cast, enrolled but not deeply so; a few rather strong crenulations can be 

 distinguished upon it indicating teeth, and the entire surface of the cast is 

 smooth; aperture quite narrow. 



Only one of the casts-present shows the enrolling of the outer lip and 

 the size and form of the aperture entire. The specimen has been slightly 

 compressed laterally, which may have somewhat exaggerated the "humped" 

 appearance of the dorsal surface, though I think not to any great extent. 

 Its form and size appear to have been somewhat like that of G. spheroides 

 Conrad, from the Jackson group, of Mississippi, described and figured in 

 Waile's Geol. of Mississippi, but not near enough to be classed under the 

 same specific name, considering the difference in position, while it is still 

 further removed from G. Mortoni Grabb, of the Cretaceous Beds in New 

 Jersey. 



