352 PALEONTOLOGY OF ILLINOIS. 



iana, Shuuiard (Trans. Acad. Sci. of St. Louis, vol. 1, p. 15), but as Dr. S. 

 gives 43 ° as the divergence of the spiral angle of his species, while that of 

 ©ur shell measures about 65°, it is scarcely possible that they can be identical. 

 Dr. S. also describes the revolving striae as being finely granose on the under 

 side of the body whorl in P. Proutiana, which is not the case with the species 

 now before us — though they are sometimes apparently obscurely crenulated by 

 the crossing of the small transverse wrinkles formed by the ^clustering of the 

 striae of growth. 



Locality and position : Hodges creek, Macoupin county, Illinois; Lower Coal 

 Measures. 



Pleurotomaria speciosa, M. and W. 



PL 28, figs. 5 a, 5 5, 5 c. 



Pleurotomaria speciosa, Meek and Worthen, Oct., 1860. Proceed. Acad. Nat. Sci., 

 Pailad., p. 459. 



Shell attaining nearly a medium size ; length slightly greater 

 than the breadth ; volutions seven to seven and a half, last one 

 forming about half the entire length,-all subangular just below 

 the suture, thence obliquely flattened, or a little concave, to a 

 distinct revolving carina, a little below the middle of the upper 

 turns, and about the middle of the body whorl. Below this 

 second much stronger angle, the outside of the last turn is 

 vertically flattened, or somewhat concave, so as to produce a 

 third more obtuse revolving prominence below the middle — 

 beneath which the under side of the whorl is convex, but not 

 ventricose. Suture well defined. Spiral band narrow, promi- 

 nent, occupying and partly forming the middle revolving angle, 

 neatly crenulated, like the milled edge of a piece of coin. 

 Aperture subcircular, approaching a subquadrate outline; um- 

 bilicus small or nearly closed. Surface ornamented by eighteen 

 to twenty-two thread-like revolving lines, about twelve of 

 which occupy the under side of the body whorl, four to seven 

 the upper slope, and two or three the outer flattened space 

 around the middle. Crossing all these, there are numerous 

 extremely fine, very regular, closely arranged, transverse lines, 



