GKOLOGY OF LA SALLE COUNTY. 



99 



istome reflected and of a roseate color; umbilicus cov- 

 ered, breadth one inch. Abundant. 



The finest species we have. Say. describes the 

 lip as white. The rosy lip is a peculiarit}^ of our 

 species. They live alone, slightly burrowed in the 

 ground — and seeming- to prefer a greensward opening 

 to a shelter beneath logs, etc. Best specimens from 

 the vicinit}^ of Indian Creek, near Fox river. 



Helix Pennsylvanica, Green. — Shell elevated, 

 whirls six, white crowded and oblique striae, umbili- 

 cus closed, aperture triang'ular, somewhat contracted, 

 lip white, reflected, a little thickened near the base, 

 color chestnut, greatest dia. 17 mill. Abundant. 



A beautiful, large species. I have always found 

 them solitary, each in its own little burrow which is 

 very nicely excavated to the depth of from two to 

 three inches, and on a high blue-grass plateau near 

 the Fox river, where there are a very few trees or 

 debris. 



Helix exoleta, Binney. — Shell large and ventri- 

 cose, six whirls, which are striated, peristome w^ide 

 and reflected, an oblique tooth process on the parietal 

 ^vall, suture distinct, aperture rounded, breadth one 

 inch. Abundant. 



Helix thyroidus, Say. — The shell has five whirls 

 with oblique stria, spire depressed, aperture lunate, 

 lip white, reflected, and at the basal portion partially 

 covering the umbilicus, tooth process on the parietal 

 w^all; horn colored, breadth nearh^ one inch. Very 

 abundant. 



Helix clausa. Say. — Shell has five whirls, is some- 

 what elevated, horn color, lip reflected, and at the 

 basal portion partially covering the umbilicus, great- 

 est dia. 18 mill. Very abundant. 



