NATURAL SCIENCES OF PHILADELPHIA. ' YY 



creasing rapidly in size, those of the spire convex, last one lar<re 

 and ventricose; suture well defined; aperture ovate; outer iTp 

 thin, extended forward and very oblique above, and broadly re- 

 treating or sinuous below the middle; columella narrow arcuate, 

 imperforate, and showing some appearance of being a little furrowed 

 below, as if for the reception of the edge of an operculum; inner 

 hp apparently not thickened above. Surface ornamented by fine, 

 very regularly and closely arranged strh-e of growth, which pass 

 very obliquely backward and downward on the upper and outer 

 side of the body volution, and then curve gracefully forward again 

 below, so as to conform to the broad sinuosity of the outer lip. 

 Height, 0.17 inch; breadth, 0.18 inch. 



This little shell will be at once distinguished from the young of 

 the last, of corresponding size, with which it agrees very nearly 

 in form, by its beautiful, very regular, well-defined, and gracefully 

 curved strife, as well as by its narrower columella, and thin inner 

 lip. The latter characters lead me to doubt whether it is not 

 more properly a Platyostoma. 



Locality and position. Same as last. 



BEILEEOPHON NEWBERRYI, Meek. 

 Shell scarcely attaining a medium size, subglobose in form; 

 volutions rounded, all hidden by the last one, the umbilicus being 

 closed on each side ; last turn expanded at the aperture, which is 

 rather large, transversely lunate or subreniform, being nearly 

 twice as wide transversely as the antero-posterior diameter ; lip 

 moderately sinuous in front, and rounded in outline on each side, 

 very thin excepting in the umbilical regions, between which it is 

 thinly spread a little over that part of the return of the spire in- 

 denting the inner or posterior side of the aperture. Dorsal band 

 rather narrow, not usually elevated above the surface of the 

 rounded dorsum, and merely defined by a slight furrow along each 

 side.* Surface ornamented by distinct, very regularly disposed 

 little transverse costge, or coarse raised lines, most strongly de- 

 fined on the dorsal side, where they curve a little backward near 

 the band, and more abruptly in crossing the latter ; while they be- 

 come finer, more curved, and directed backward in approaching the 



1 In one of the smaller specimens, the band is a little raised so as to form 

 a slight ridge. 



1871.] 



