162 Trans. Acad. Set. of St. Louis. 



formed below the convexit}^ of the body whorl, and a spiral 

 sculpture of coarse subequal Ijrae. The embryo is conoidal, 

 compact and closely coiled, multispiral, or composed of about 

 three whorls. The body whorls are evenly convex and 

 coarsely ribbed, the subsutural collar not well defined. The 

 columella is biplicate. The two species before me are both 

 from the Upper Claiborne ferruginous sand, and may be defined 

 as follows : — 



Form very stout, the spiral lyrae coarser and more close-set, separated by 

 scarcely their own width on the peripheral convexity, though widely 

 separated below on the body whorl; columellar plicae moderately 

 strong and extremely oblique. Length of a specimen of 5 body whorls, 

 17.5 mm.; width, 7.5 mm. [Fmsms] plicata Lea 



Form less stout, smaller in size, the spiral lyrae finer, separated by about 

 twice their width on the convexity of the body whorl, the central of 

 the fine intermediate threads more pronounced than in plicata; 

 columellar plicae very strong and much less oblique. Length of an 

 equally well grown specimen of 5 body whorls, 13.5 mm.; width, 5.5 

 i^™ extricata n. sp. 



Varieobela n. ojen. 



The shell here is of moderately large size, thick substance 

 and very stout form, with strongly elevated rounded varices, 

 usually about five in number on the first four body whorls. 

 The embryo is large, broadly and regularly conoidal, much 

 wider than high and composed of about three whorls. The 

 body whorls are broadly and evenly convex, without 

 pronounced peripheral prominence, having numerous long 

 and rather narrow, elevated and obliquely sigmoid ribs 

 and many fine lines of growth, which are cut by equally 

 fine and regular spiral threads, producing a regular 

 but very minute clathration ; every fourth spiral thread 

 is larger, these becoming strong and widely spaced lyrae on 

 the body whorl below the convexity ; aperture half as long as 

 the shell, oblique, the canal very short but narrow and rather 

 well differentiated. The inner lip is callous throughout and 

 there are no columellar plicae. The type of this genus, 

 rendered very isolated by the varices so unusual in the Pleuro- 

 tomidae, is the Sfrotnbus smithi, of Aldrich, occurring in the 

 upper Eocene strata at Red Bluff, Miss. A specimen of 4 



