GASTEROPODS. 139 



Shell of medium size, subglobose ; whorls five to six in num- 

 ber, regularly rounded. Aperture subcircular. Surface orna- 

 mented by twenty to thirty sharp, revolving carinae, with 

 broadly rounded, concave furrows between ; these are crossed 

 by fine, sharply defined lines of growth. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



The original specimens of this species are from Williamson 

 county, Illinois. A very similar form has been described from 

 Newport, Indiana, under the name P. neivportensis. Apparently 

 the only difference ascribed is that it has the revolving band 

 raised instead of depressed. Further comparisons may show, 

 eventually, this character varietal rather than specific. This 

 suggestion seems all the more plausible since many individu- 

 als which are unquestionably P. carbonaria have the band 

 scarcely sunk below the general surface. The various exam- 

 ples of the species under discussion vary considerably in 

 height; and Miller's recently described P. harii is merely one 

 of the more depressed phases. 



Pleurotomaria illinoisensis WORTHEN. 



Pleurotomaria depressa Cox, 1857 : Geol. Sur. Kentucky, vol. Ill, p. 569, 



pi. viii, figs. 10-10a. (Not Passy, 1832.) 

 Pleurotomaria illinoisensis Worthen , 1884: Illinois St. Mus. Nat. Hist., 



Bui 2, p. 4. 

 Pleurotomaria modesta Key es, 1888: Proc. Acad. Nat. ScL, Phila., p. 238, 



pi. xii, figs. 2a-b. 



Pleurotomaria kentuckensis Miller, 1890 : N. A. Geol. and Pal., p. 421. 

 Pleurotomaria illinoisensis Worlhen, 1891: Geol. Snr. Illinois, vol. VIII, 



p. 135, pi. xxiii, figs. 6-6b. 

 Pleurotomaria modesta Keyes, 1891 : Proc Acad. Nat. Sci., Phila., p. 252- 



Shell small, lenticular ; spire greatly depressed ; volutions 

 about six in number, obliquely flattened above; body-whorl 

 large, rapidly increasing in size, sharply angular on the periph- 

 ery, flattened or even slightly concave above, broadly rounded 

 below; suture very slightly impressed; peripheral band not 

 well defined, and on the spire still more obscured by a single 

 series of prominent nodes; aperture subquadrate; umbil- 

 cate region slightly impressed, but not perforated ; surface 

 glabrate, but showing fine lines of growth under a magnifying 



