722 GEOLOGICAL SURVEY OF IOWA. 



Pleurotomaria sphserulata. 



PLATE XXIX. FIG. 13. 



P leurotomaria spharulata : CONRAD, Journal of the Academy of Natural Sciences, Vol. 



viii, pa. 272, pi. 16, f. 12. 



P leurotomaria coronula : HALL in Stansbury's Keport, pa. 413, pi. 4, f . 6 a, b, c, d [by 



error pi. 2, f . 6 a, b, c, d ] . 



SHELL subglobose, semiglobose, or depressed conical, with 

 the angles more or less rounded. Spire more or less elevated, 

 often subtruncate above : volutions about five or six, the 

 last one angular on the periphery ; aperture quadrangular, 

 subrhomboidal ; umbilicus none ; suture-line marked by an 

 elevated band, which is studded with rounded or subangular 

 nodes. 



SURFACE marked by fine strise parallel to the lines of 

 growth, which bend abruptly backwards on the periphery, 

 curving forwards on the base, and bending backwards to- 

 wards the centre to a spiral band, which follows the direction 

 of the columella. 



This shell is sometimes very variable (fronvpressure or other causes) in the eleva- 

 tion of the spire and angularity of the last volution. The specimen figured is one 

 having the spire unusually elevated. 



Fig. 13 a. Anterior view of specimen. Fig. 13 b. View of the aperture. 



Geological position and localities. In the Coal formation of Indiana, Illi- 

 nois, Iowa, Missouri, and Kansas. 



Euomphalus rngosns ( n. s.). 



PLATE XXIX. FIG. 14 a,b,c. 



Compare Inachus catilloides ; COJJKAD, Journal Academy Natural Sciences, Philadelphia, 



Vol. viii, pa. 273, pi. 15, f. 3. 



SHELL discoidal, nearly flat and slightly oblique on the 

 dorsum, both sides concave from the outer margin to the 

 centre ; margins of the outer volution unevenly carinate or 

 nodose carinate : all the volutions exposed in the broad 

 shallow umbilicus. Spire slightly depressed, showing about 

 four volutions. 



