56 FRANK COLLINS BAKER 



although it probably occurs and has been listed as pulchella or 

 costata. McGee's reference to pulchella from Fulton, Whiteside 

 County {Pleistocene History of Northeastern Iowa, p. 448) may be 

 this species, as it looks like that species without the aid of a powerful 

 magnifier (Baker, 19206, p. 351). It probably occurs widely 

 distributed in northwestern Illinois. Living gracilicosta are 

 known only from the West and Canada. Its abundance in the 

 loess indicates a former greater southward extension in distribution. 



Succinea ovalis Say. Fragments of a large Succinea from the 

 Peorian loess near Peoria are believed to be this species. 



Succinea avara Say. Several specimens of a species referable 

 to true avara occurred in the loess of Whiteside County. 



Succinea vermeta Say. The great majority of Succineae col- 

 lected by Dr. Leighton are referable to Say's vermeta, which appears 

 distinct from his avara, the spire being longer, the sutures deeper, 

 the whorls rounder, and the aperture roundly ovate instead of 

 long ovate. The shells referred to vermeta vary among themselves, 

 but all are easily separable from typical avara. Avara as recorded 

 from Pleistocene deposits also includes vermeta, the two forms not 

 being differentiated. The two forms are said to intergrade com- 

 pletely in the Recent fauna, but this does not seem to be true of 

 the Pleistocene fauna, at least as shown by the material examined. 

 The localities represented in the collections of Dr. Leighton are: 



Sangamon sand, Irene, Boone County. 



Early Peorian loess, Winslow, Whiteside County. 



Peorian loess, Stevenson County. 



Wabash sand, Carroll County. 



Wabash silt, Whiteside County. 



Vertigo modesta Say. This small land shell (of which the 

 Pupilla hlandi Morse of the Iowa deposits is a synonym) occurred 

 sparingly in three places, in silt and sand, Carroll County, and in 

 loess, Whiteside County. The individuals from silt and sand 

 deposits are apparently typical with four teeth in the aperture; 

 but the loess specimen from Whiteside County is different from any 

 form described. There are a columella tooth and two palatal 

 teeth, but no parietal tooth. Pilsbry (1919, p. 128) describes a 

 toothless and a tridentate form of modesta from Norton Sound, 



