172 PALEONTOLOGY OF KENTUCKY. 



next to the baud is of about equal depth with the furrow in the upper half ; 

 the second depression in the lower half is shallow. In consequence of the 

 great convexity of the volutions the suture is deep. The character of the 

 transverse striae is only indicated but not fully known. 



Formation and Locality. In Hie Cornifcrous limestone in Jefferson county, Ky., and in Clark 

 county, Ind. My specimen is only an internal cast, from which the surface-markings, with the exception 

 of the revolving ctirmae, are obliterated. 1 have compared this shell with all the different species of Pleu- 

 rotomaria known to me, but can not place it with any one, and 1 am thus compelled to make a new species 

 for its reception. 



Pleurotomaria lucina. HALL. 



Kuomphalust rotundas, Hall. Geol. of N. Y., Surv. of 4th Di&t. 1843. 

 Pleurotomaria lucina, Hall. Descpt. of New Sp. of Foss., p. 141861. 

 Pk'iirolomaria liicirut, Hall. Fifteenth Keg. Kep., pi. 42 18G2. 

 Pkur. rotunda and P. lucim, Hall. 111. of Dev. Foss. Gastrop, pi. 8 187G. 

 Pleur. lucina, Hall. Pal. N. Y., Vol. 5, part. 2, p. G7 1879. 



Shell sub-globose or obliquely ovoid-conical. Spire moderately elevated ; 

 apex minute ; volutions about four, gradually expanding to the last one, which 

 comes very regularly ventricose, with the aperture expanded and nearly round, 

 extended on the lower side, with a shallow notch on the anterior margin ; upper 

 side of the volutions very symmetrically convex ; suture neatly defined, 

 slightly canaliculate ; lower side of the body- volution convex in the middle, 

 and abruptly curving into the umbilical depression. 



Surface beautifully cancellated by concentric and revolving striae, which, in 

 many specimens, are of equal strength. Periphery marked by a moderately 

 wide band, on which the striae are turned abruptly backwards ; this band is 

 limited by stronger striae or narrow ridges on each side, sometimes with one or 

 two slender revolving striae within the limits of the band, making a narrow 

 space, which is often crenulated by the concentric striae. 



This species is well marked by its symmetrically rotund form, with moderate 

 elevation of the spire, and the regular convexity of the volutions, even in casts 

 of the interior when not compressed. There is some variety in the surface- 

 markings of specimens apparently belonging to this species. The concentric 

 striae are sometimes much coarser than the revolving ones ; and finer striae are 

 implanted between the stronger ones, and do not reach the suture-line. In 

 old specimens the revolving band is sometimes nearly a quarter of an inch 

 wide. A very symmetrical specimen has a diameter of a little more than two 

 inches, and is nearly an inch and three-fourths in height. 



Formation and Locality. Found in the Cornifcrous limestone, at and around the Falls of the 

 Ohio, in Kentucky and Indiana, but generally as internal casts, which show only the general form, but not 

 the surface-markings of the shell. 





