OF CONCHOLOGY. 261 



MONOPTIGMA, Lea. 



MoNOPTiGMA Leai. — t. 27, f. 7. 



Description. — Shell of medium size, with an elevated pointed 

 spire; volutions about five, ventricose above, and attenuate 

 below; suture distinct or slightly channelled ; columella a little 

 twisted in the lower part, with a strong, slightly oblique fold 

 above the middle ; aperture nearly three-fifths of the entire 

 length of the shell, deeply notched at the anterior end; sur- 

 face marked by a line of small nodes just below the suture, 

 most distinct on the upper parts of the shell. 



Dimensions. — Length of medium-sized specimen '8 inch, 

 transverse diameter of body volution '35 inch. 



This species differs from any species of the genus hereto- 

 fore described, in the possession of the revolving line of nodes 

 on the upper margins of the volutions. 



Locality. — Vicksburg, Miss. Uj)per Eocene. 



COLUMBELLA, Lam. 



COLUMBELLA TURRICULA. — t. 27, f. 1. 



Description. — Shell small, polished, sub-fusiform ; spire much 

 elevated ; volutions six (seven ?) slightly convex or flattened 

 on the surface; suture grooved; aperture elongate-elliptical 

 forming nearly one-third of the entire length of the shell; 

 upper angle acute, strongly truncate at the base ; outer lip 

 thickened, with about seven proportionally strong dental pro- 

 jections; inner lip with about six smaller crenulations, corre- 

 sponding to a similar number of oblique revolving ridges on 

 the somewhat contracted columella; canal short and wide. 



Dimensions. — Length '20 inch, greatest transverse diameter 

 •07 inch. 



Locality. — Claiborne, Alabama. 



PLEUROTOMA, Lam. 



Pleurotoma capax. — t. 27, f. 3. 



Description. — Shell small, broadly-fusiform; volutions five, 

 strongly concave on the upper side, and ventricose below; 

 ornamented on the periphery of the upper volutions with a 

 line of nodes, whicb gradually decrease in size, and finally 

 become obsolete on the body whorl; columella strong, slightly 

 twisted in the lower part; aperture wide, and, with the canal, 

 forming more than one-half the entire length of the shell; 

 surface marked by very fine, tortuous, revolving lines, very 

 faint on the concave part of the volutions; crossed by fine 

 lines of growth, having a slight curve in the upper part. 



