138 PALAEONTOLOGY OF ILLINOIS. 



Length of the three lower volutions 1% inches ; greatest breadth 

 1% inches. 



Collector, A. H. Worthen. 

 No. 2493 of the Illinois State Museum. 



PEUROTOMARIA IOWENSIS. (sp. nov.) 



PL XXIV. Fig. 2. 



Pleurotomaria Coxana, Worthen, March, 1884. Bulletin No. 2 of the Illinois State 

 Museum of Natural History, page 6. 



When this species was described in 1884, the fact that the 

 specific name coxana, was already occupied for a Coal Measure 

 form was overlooked, and therefore the name iowensis is 

 now substituted for the one originally proposed. 



Shell large, broadly umbilicated, spire moderately extended, 

 its length being equal to about one-third the full length of the 

 shell; volutions about four, strongly and evenly convex above, 

 and increasing gradually in size, the last one abruptly rounded 

 below into the umbilicus; aperture apparently subovate. The 

 specimen is a cast in limestone, and the surface was probably 

 nearly smooth, as the fragments of the adhering test show no 

 external markings. 



Length 2% inches; breadth 1% inches; diameter of the last 

 volution 1 6 / 1(J inches. 



Position and locality: Keokuk limestone, Keokuk, Iowa. 



Collector, Mr. L. A. Cox. 



No. 2547 of the Illinois State Museum. 



GENUS PORCELLIA, Leveille. 

 POECELLIA PEORIENSIS. Worthen. 



PL XXIII, Fig. 4-4a, 4b. 



Porcellia Peoriensis, Worthen, March, 1884. Bulletin No. 2 of the Illinois State Museum 



of Natural History, page 6. 



Shell small, volutions about five, closely embracing and very 

 gradually enlarging, the last one marked by a narrow dorsal 

 band, defined by a sharp elevated ridge on either side. Outer 

 volution ornamented also with a row of about nine small nodes 



