272 PROCEEDINGS OP THE ACADEMY OF 



Locality and position. Hodge's Creek, Macoupen County, 111. Lower Coal 

 Measures. 



Pleurotomaria Coxana, M. & W. 



Shell attaining a large size, obliquely conoid-subtrochiform, longer than 

 wide; spire turreted, forming rather more than half the entire length. Vo- 

 lutions six to seven, convex, very prominent or obtusely subangular below the 

 middle, at which point those of the spire project out over the suture ; all flat- 

 tened or slightly concave above, with an outward slope of about 35 to the 

 axis, from the suture to the most prominent part, where the spiral band is 

 placed ; below this the underside is rounded convex to the small umbilical 

 perforation. Suture strongly defined by the convexity of the whorl just 

 above it. Aperture subquadrate. approaching subcircular in adult shells. 

 Surface ornamented by exceedingly fine, regular lines of growth, that run 

 very obliquely backwards, with a slight forward curve in passing down the 

 sloping upper side from the suture to the spiral band at ihe most prominent 

 part of the whorls ; between this and the umbilical perforation below they 

 make a backward curve. Casts also show some traces of much stronger re- 

 volving lines in the umbilical region. 



As is not uncommon in species of this type, the divergence of the apical 

 angle varies considerably with age, being greater in young than adult shells. 

 In internal casts there is a moderately distinct umbilical perforation, which 

 seems to be very small, or nearly closed in specimens retaining the shell. 

 The lines of growth are exceedingly fine and regular, without any traces of 

 revolving striae, excepting near the umbilicus, and we are not sure they really 

 exist there, as only traces of apparently such lines have been seen. 



This shell will be readily distinguished from all of those known to us, ap- 

 proaching it in size, such as P. tabulata, Conrad, and P. su/jscalaris, M. & W., 

 by its more oblique form, more sloping and less angular whorls, as well as 

 by the absence of any traces of revolving stria? on the upper slope of its whorls. 



The specific name is given in honor of Prof. E. T. Cox, of New Harmony, 

 Indiana, to whom we are indebted for the use of the best specimen of the spe- 

 cies we have seen. 



Locality and position. Iron ore beds of Lower Coal Measures, at Nolan's 

 Furnace, Edmondson Co., Kentucky. 



Plecrotomaria spironema, M. & W. 

 i 



Shell rather under medium size, subglobose, its length and breadth being 

 nearly equal. Volutions five to six, increasing rather rapidly in size ; those 

 of the spire convex ; the last one forming more than four-fifths of the entire 

 length, and as much as nine-tenths the entire bulk of the shell, rounded 

 regularly from the suture above to the umbilical region below, excepting 

 near the aperture, where it is a little more prominent below than above the 

 middle. Suture well defined. Aperture subcircular in general outline, but 

 rather strongly modified above the middle on the inner side, by the return of 

 the body whorl. Inner lip slightly thickened a.nd deeply arcuate below, but 

 wanting or exceedingly thin above the middle of the aperture ; columella tortu- 

 ous, with a slightly impressed furrow at the outer margin of the inner lip, 

 but without an umbilical perforation. Surface ornamented with regular, dis- 

 tinct revolving striae, crossed just below the suture by short little regular node- 

 like folds, confined to the narrow space between the suture and the spiral band ; 

 similar, but smaller, more crowded and longer curved wrinkles also radiate 

 from the umbilical region, on the under side of the body whorl. Lines of 

 growth obscure on all the specimens examined. Spiral band flattened so as 

 to be even with the general surface, nearly smooth, and placed half-way be- 

 tween the middle of the body whorl and the suture above, or about once and 

 a half its own breadth below the suture. 



[July, 



