POLYGYRIDAE 



55 



POLYGYRA ELEVATA (Say) 



This species of Polygyra has been called elevata because of 

 the very high spire characteristic of its shell. This shell has 6 

 full whorls, a greater number than is found in many of the 

 larger snails. Aside from the large 

 yellowish spire standing up like a 

 beehive, the most noticeable feature 

 of elevata is the heavy, tonguelike 

 denticle on the parietal wall. The 

 shell has also a small indistinct 

 swelling on the lower part of the 

 peristome. The size of this shell 

 has been found to vary consider- 

 ably, from three-fourths inch to about an inch (19-25 mm.) in 

 diameter, but all sizes may and do occur in the same colony. 



The animal is light brown on the upper surface and lighter 

 on the sides and the posterior part. 



This snail with the elevated shell is most abundant in 

 ravines where there is a heavy growth of oak, maple, hickory 

 or sycamore trees and a considerable cover of forest debris. It 

 is very plentiful wherever it is found, but it is at present known 

 in Illinois only from Fulton, Vermilion, Clark, Lawrence, 

 Madison, Jackson and Alexander counties. 



v^OLYGYRA PEN N SYLVAN I CA (Green)* , 



The yellowish shell of Polygyra pennsylvanica, about three- 

 fourths inch (16-20 mm.) in diameter, appears to be almost a 

 miniature example of the species Polygyra elevata. Both have 

 a high spire and are imperforate, 

 but pennsylvanica lacks the heavy 

 denticle on the parietal wall and it 

 has no denticles on the peristome. 



The animal is lead colored, with 

 the under part of the foot a lighter 

 color. 



This species is widely distrib- 

 uted over Illinois and is found in the same habitats as Polygyra 

 elevata: in ravines where there is a heavy growth of oak, maple, 

 hickory or sycamore trees. 



