356 PALEONTOLOGY OF ILLINOIS. 



regularly arranged striae, which are much more distinct near 

 the suture on the upper slope than below the band, mark the 

 whorls transversely. Length, 0.24 inch ; breadth, 0.20 inch ; 

 apical angle a -little convex, divergence 60°. 



We have seen but a single specimen of this little shell, yet it differs suffi- 

 ciently from all the other species we have met with from these rocks, to he 

 readily distinguished. Amongst its most marked peculiarities, that may he 

 mentioned, are the prominently rounded, or ventricose character of the under 

 side of its body whorl, and the extreme narrowness of its spiral band, with its 

 prominent marginal carinae. We know of no species very closely allied to 

 it from foreign localities. 



Locality and position : Springfield, Illinois ; Upper Coal Measures. 



Pleurotomaria granulo-striata, M. and W. 



PL 28, fig. 2a, 2b, 2c, 2d. 



Pleurotomaria granulo-striata, Meek and Worthen, October, 1860. Proceed. Acad. Nat. 

 Sci., Philad., p. 459. 



Shell very small, conical-subovate, or subtrochiform ; spire 

 moderately elevated ; volutions compressed-convex, last one 

 prominently rounded or subangular around the middle ; suture 

 well defined ; aperture apparently subcircular ; spiral band 

 not distinctly defined, located near the middle of the body 

 whorl, and passing around just above the suture on the other 

 turns ; calumella imperforate ; surface ornamented by about 

 twelve or thirteen comparatively distinct revolving lines, eight 

 of which occupy that portion of the body whorl below the 

 band, where they are a little smaller and more closely 

 arranged than above. 



On the upper sloping side of the whorls, the three or four 

 revolving lines occupying that part of the shell are crossed 

 obliquely by transverse lines, which are so much stronger on 

 the revolving strige than between them, that they present the 

 appearance of small nodes or granules at the points of crossing. 



