PLEISTOCENE MOLLUSCA FROM ILLINOIS 55 



variation in the height of the spire and the width of the shell. 

 This is the first record for the species in the Pleistocene deposits of 

 Illinois, though it is common in the Recent fauna. 



Calha parva (Lea). Three lots of a small lymnaeid apparently 

 referable to parva were collected by Dr. Leighton, in brown sand 

 and yellow sand, Carroll County, and in silt, Whiteside County, 

 the latter in post- Wisconsin deposits (Wabash age). In one lot 

 from yellow sand (see Station No. 8) the shell is very wide and con- 

 vex on the body whorl. This shell resembles Wolf's figure of his 

 tazewelliana, described from deposits in Tazewell County (Wolf, 

 1870, p. 198, PL XVII, Fig. 2). This form is much more obese in 

 the body whorl than are individuals of this species from the Recent 

 fauna. Specimens from silt in the same section have a much 

 narrower and more compressed body whorl, and the columella is 

 slightly impressed. A single adult individual from Whiteside 

 County (silt deposit) has the columella impressed so as to form a 

 slight plait. The material at hand is not sufficient to separate these 

 forms satisfactorily, or to indicate whether they are merely local 

 sports or larger variations. On the whole, if these are merely 

 individual variations, the parva of the late Pleistocene is much 

 more variable than its living representative. 



LAND GASTROPODS 



Helicina occulta Say. A number of individuals of this species 

 occurred in Peorian loess near Peoria. It is not a pulmonate land 

 snail. 



Carychium exile H. C. Lea. A single individual of this small 

 snail occurred in the peat deposit in Carroll County. It is quite 

 typical. 



Vallonia gracilicosta Reinhard. Seven specimens of a Vallonia 

 occurred in the loess deposit of Whiteside County that are referable 

 to gracilicosta. They exactly conform to the figures by Sterki (1892, 

 p. 256, PL XXXIII, Figs. 48, 49) and they agree with his descrip- 

 tion, having the fine, distinct ribs characteristic of this species, 

 which are finer and differently spaced than those of costata. Gracili- 

 costa, according to Shimek, is a common loess fossil in Iowa. It 

 has not previously been positively identified from Illinois deposits, 



