354 PALAEONTOLOGY OF ILLINOIS. 



This handsome, symmetrical little shell has much the form and general ap- 

 pearance of a /Solarium., excepting that it has no umbilicus, and possesses the 

 peculiar spiral band characteristic of the genus Pleurotomaria. On the upper 

 part of the whorls, the transverse striae crossing the revolving lines are very 

 regularly arranged, at intervals a little greater than their own breadth, but in 

 crossing the spiral band they become more crowded, and curve gracefully back- 

 wards, parallel to the sinus of the lip. They are also rather closely and very 

 regularly arranged on the under side of the body whorl. 



Locality and position: Same as last. 



Pleurotomaria brazoensis, Shumard? 



PI. 28, figs, la, 16, 1 c, Id. 

 Pleurotomaria brazoensis, Shumard, 1860. Trans. St. Louis Acad. Sciences, i, p. 624. 



Shell rather under medium size, trochiform, height and 

 breadth nearly equal. Volutions five and a half to six, 

 obliquely flattened or a little concave above; last one com- 

 posing about half of the entire length, flattened or slightly 

 convex below, and very prominent around the middle, where 

 it is provided with two nearly equal carinae, between which is 

 located the band of the sinus. On the spire only the upper of 

 these carinae is seen above the suture. Just below the well 

 defined suture the upper edge of the whorls is a little thick- 

 ened so as to form a subangular prominence, which is provided 

 with a series of small, obscure nodes. Aperture subquadrate 

 or subrhombic; columella perforated. Surface ornamented by 

 about twenty-five small, thread-like, revolving lines, some 

 twelve or thirteen of which occupy the underside of the body 

 whorl; crossing all these are numerous similar, equidistant, 

 transverse strise, the whole forming a regular cancellated style 

 of ornamentation. Length, 0.43 inch ; breadth, 0.41 inch ; 

 spiral angle nearly regular, divergence, 70 °. 



Being in doubt whether or not this species is really identical with Dr. Shu- 

 mard's P. brazoensis, we have preferred to describe our specimens instead of 

 quoting his carefully written diagnosis. They seem to agree very closely with 



