THE GASTROPOD GENUS WANIA 29 



The lateral slope of the whorl below the outer edge of the slit hand is 

 somewhat narrower than the upper slope. It is smooth and broadly concave, 

 and is hounded below by the most prominent COSta on the whole shell. Growth 

 lines have not been observed upon this part of the whorl. 



The basal slope of the whorl hears a prominent eosta within and below 

 the larger one which marks the boundary between this part of the shell and 

 the lateral surface. They are separated by a space somewhat less than the 

 width of the slit hand. Upon the inside of this costa is a shallow concave 

 furrow similar to those which separate the costae on the hasal surface of 

 other species in this genus, hut in this case no costa rises upon the inside of 

 it and the hasal surface is smooth for the remainder of the distance to the 

 columella. Tt is entirely possihle that the hasal surface was originally orna- 

 mented by additional spiral costae that have heen destroyed and do not appear 

 upon the imperfectly preserved specimens examined. This is indicated hy 

 one specimen which preserves indistinct traces of a few fine costae adjacent 

 to the columella. On the other hand this species is closely similar to Y. 

 adamsi, upon the central part of the hase of whose whorls I have never 

 observed costae, a fact suggesting that most of the hasal surface of the species 

 under discussion was probably smooth. No lines of growth have been ob- 

 served upon the hasal slope of the whorl. 



Remarks. — The specimens upon which the species Yvania salinensis is 

 erected are poorly preserved as compared to other forms described in this 

 paper. Although much of the surface detail has heen destroyed, enough 

 remains to characterize this species in a reliable manner. It is possihle that 

 the future discovery of more perfect specimens will reveal some more delicate 

 surface markings than those described above. 



Yvania salinensis is closely related to Y. adamsi from which it may he 

 distinguished by the more acute spiral angle, the more convex base, the less 

 concave lateral slope and the single costa which marks its lower limit, and 

 the sharply impressed suture. 



The holotype of this species is No. 5 in the collection of the Illinois 

 State Geological Survey. 



Occurrence. — This specie- occurs in the limestone cap rock of the I lerrin 

 (No. 6) coal at the rairoad cut in the SW. '4 NW. % sec. 31. T. 9 S.. 

 R. 6 E., near Ledford, Saline County, Illinois. 



