226 PALEONTOLOGY OF NEW JEKSBY. 



between these two extremes. Considering that these variations occur in the 

 shells, when the substance is preserved, among those recognized as of the 

 same species, I conclude this may easily . represent one of them, more 

 especially as only a single individual has been seen for comparison. 



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

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



NATICID^. 



Genus NATICA Lamarck. 



Natica globulella n. sp. 



Plate XXXIV, Figs. 1-4. 



Shell small, not exceeding half an inch in its greatest diameter, and 

 depressed globular in form, being somewhat broader than high, as seen in 

 internal casts, with a moderately rounded spire; volutions rotund, with 

 strongly marked sutures and apparently about four in number, only three 

 to three and a half showing in the cast; umbilicus open and of moderate 

 size, no evidence existing of a callus or thickened columellar lip; aperture 

 semilunate, rounded below and apparently narrowly, rounded above; sur- 

 face destitute of markings, so far as can be detected on the casts, though 

 the matrix has not been examined. 



This species, in its general form and proportions, resembles 'N. (Luna- 

 tia) semilunata Lea, but the umbilicus appears to have been entirely open 

 and too large for that species, and its form, as revealed by the casts, would 

 not indicate it as a Lunatia. It is possible it may have been identical with 

 some one of the several species of naticoid shells known from the Claiborne 

 or lower beds of the southern Eocene, but as far as its characters are 

 revealed, I should greatly doubt it. 



Formation and locality: In the upper layers of the Upper Grreen Marls 

 at Shark River, New Jersey. In the collections at Rutgers College and 

 Am. Mus. Nat. Hist. 



