STROBILOPSIDAE 



115 



Strobilops aenea m'lcromphala Pilsbry. The mlcromphala 

 variety of Strobilops aenea is dis- 

 tinguished by a narrower umbilicus 

 than is found in many forms of the 

 genus Strobilops. Only the parietal 

 lamella emerges from the aperture, 

 and but 2 or 3 basal folds may be 

 seen through the translucent base of 

 the shell. The form of micromphala 

 is more convex than that of the 

 typical aenea, and the color is cin- 

 namon-brown without the golden tint of the typical species. 

 The shell of micromphala is less than one-eighth inch (2.0- 

 2.5 mm.) in diameter. 



The variety micromphala is common to the lower Mississippi 

 Valley and to the southwest in Arkansas and Louisiana. The 

 present Illinois records, from White, Washington and Hardin 

 counties, are the most northern known. The habitat of this 

 form is in woodland areas similar to some of those inhabited 

 by Strobilops aenea aenea. 



Strobilops aenea spiralis Pilsbry. A very rare Strobilops, 

 the variety spiralis may be known by 

 its broad turban-shaped spire, its light 

 brown color and particularly by its 

 parietal lamella, which is very long 

 and makes nearly or almost a full 

 turn of a whorl. The other parietal 

 lamellae are deep seated, also. The 

 basal folds are placed deep within the 

 whorl. The race spiralis is distinct in 

 its shape and in the position of the 

 parietal lamella. It is known in Illi- 

 nois only from Union County, where 

 it is found in the heavily wooded hill 

 region at Alto Pass. The size is less 

 than one-eighth inch (2.5 mm.) in 

 diameter. 



This snail was first observed in 

 Logan County, Arkansas, and its previously published localities 

 include only Wyandotte, Indiana, and two localities in Alabama. 

 The Illinois record adds another state to the distribution list. 



