2S)8 PALiEONTOLOGY. 



ami in tlio more anterior position of its beaks, as well as in the want of 

 convexity in the curvature of the antero-cardinal border, as would be 

 required were it a sjiecies of Tancredia. 



Formation and locality. — In red sandstones of Triassic or Jurassic? age, 

 North head of Chalk Creek, Utah. Picked up in the debris, and of no 

 stratigraphical importance. 



GASTEROPODA. 



Genus NATICA Lam. 



Natica? Lelia n. sp. 

 riato Vn, figs. 19-21. 



Shell small, globose; height and width about equal, and seldom exceed- 

 ing a fifth of an inch in measurement. Volutions two and a half to three, 

 the last one very rapidly expanding and ventricose, constituting almost the 

 entire bulk of the shell; inner volutions minute, moderately elevated above 

 the surface of the body-whorl, and somew^hat regularly rounded, forming a 

 very low spire; suture distinct but not channeled; aperture subpatulose or 

 pear-shaped, higher than wide, largest below the middle, pointed at the 

 ujjper extremit}' and rounded below, except near the junction with the col- 

 umella, where it is almost subrimate; outer lip thin and sharp. Columella 

 arcuate, rounded, without an}^ appearance of a callus or thickening of any 

 kind as far as can be determined, from any of the examples in hand. (This 

 portion of the shell is more or less concealed by adhering rock in all the 

 individuals, so that this feature cannot be satisfactorily determined.) The 

 stria^, however, appear to pass from the body of the shell directly upon and 

 over the solid, sKghtly-twisted, and non-umbilicated columella. 



Surface of the shell smooth, appearing almost polished, except for the 

 very line stri;c of growth which aro directed backward across the body of 

 the volution. 



Tlie species has nearly the size and general appearance of Nativopsis 

 nana ileek and Worthen, from the Coal-Measures of Illinois and the West, 

 but differs in the columella being less straightened and prolonged below, 

 not giving so great a basal extension to the aperture. The diflf'eronces of 

 the character of the columella are too distinct to require comparison. Tlic 



