POLYGYRIDAE 



51 



POLYGYRA MULTILINEATA (Say) 



Most specimens of Polygyra multilineata have dark brown 

 bands on a horn-colored background. The field records indicate 

 that Polygyra multilineata is more abundant in northern than 

 in southern Illinois; nevertheless, 

 some of the finest specimens have 

 been collected near Cairo, Alex- 

 ander Count)'. This Polygyra is 

 usually found along the edges of 

 swamps, in low ground subject 

 to overflow or in damp woods of 

 oak, hickory, box elder, tamarack, 

 maple or cottonwood. 



The animal is generally black- 

 ish, but with granules which are 

 whitish; darker zones lie between 

 the granules. The under part of 

 the foot is black. 



Several varieties of multiline- 

 ata are known. 



Polygyra multilineata multilineata (Say). Fig. A. The shell 

 of the typical variety is about an inch (23-28 mm.) in diameter. 

 The bands nearest the periphery are widest. 



Polygyra multilineata algonquinensis Nason. Fig. B. The 

 shell of this variety is a little more than one-half inch (16-18 

 mm.), slightly more than half as large as the usual size of 

 multilineata multilineata. In some specimens the color bands are 

 distinct and in others the shell is almost devoid of color orna- 

 mentation. The umbilical region is rather deeply impressed, and 

 in many specimens there is a little slit or chink behind the 

 reflected lip which forms a false umbilicus. The aperture of this 

 variety is not so nearly round as that of the typical form. It 

 is known in Illinois from McHenry, Kane and Cook counties. 

 It was discovered near Algonquin, Illinois. 



Polygyra multilineata alba and rubra Witter. These are 

 color variations, shells of the first being whitish or yellowish 

 and those of the second reddish or brownish; both are without 

 color bands of any kind. Each has a shell about three-fourths 

 inch (20 mm.) in diameter. The rubra form is common in 

 Illinois, but the alba form is rare in this state. 



