GASTEROPODA OF THE LOWEE GREEN MARLS. 63 



Genus SERRIFU8US Meek. 



Serripusus ? Crosswickensis, n. sp. 



Plate V, Figs. 34, 25. 



Shell small or of medium size, biturbinate in form, shorter below than 

 above the middle, exclusive of the beak, the extension of which is unknown, 

 casts only having been observed; spire broadly conical, the apical angle 

 measuring about 55°; volutions about four and a half or five on the inter- 

 nal cast; angularly ventricose, vertical or concave on the periphery, the 

 latter character particularly a feature of the body volution; upper side 

 of the volutions obliquely sloping, the slope being somewhat greater than 

 the angle of the spire, so as to reveal the vertical portion of each volution; 

 lower side rounded; aperture nearly as broad as high, as seen in a transverse 

 section, the outer lip slightly biangular, corresponding to the narrow vertical 

 band of the periphery; columella strong, indicating a rather robust beak; 

 surface features unknown. 



This species differs from S. nodocarinatus, herein described, in having a 

 less elevated and broader spire; in having a vertical peripheral band, and 

 in being destitute of the transverse nodes on the peripheral carina, so far as 

 can be seen on the cast. There is a slight indication of a single spiral ridge 

 a short distance below the central band, but it is hardly definite enough on 

 the cast to be given as a positive feature, and it is also possible there may 

 have been nodes on the carinations formed by the band, but there are no 

 indications of such a feature remaining. Were it not for the very evident 

 rostral beak, although probably very short, there might be reasons for con- 

 sidering the casts those of a species of Pleurotomaria, but the existence of 

 this feature would entirely remove it from that group of shells, although 

 many of the Palaeozoic forms referred to that genus present a short, straight 

 columella; but here there has been, I think, without question, a true rostral 

 beak and canal. 



Formation and locality: In the blackish marls at the base of the Lower 

 Green Sands at Crosswicks, New Jersey. Collection at Eutgers College. 



