34 ILLINOIS NATURAL HISTORY SURVEY MANUAL 



from foreign countries into greenhouses and other places in 

 cities. The native fauna, therefore, comprises 116 species and 

 faces. These are divided among 14 families and 28 genera. 



It is of interest to compare this fauna with that of other 

 states. The modern classification and nomenclature of the 

 land Mollusca represent such changes from those in use a few 

 years ago that only five catalogs are at present available for 

 direct comparisons. These relate to the fauna of Michigan 

 (Winslow, 1936), Ohio (Sterki, 1907), Pennslyvania (Brooks, 

 1931), Indiana (Daniels, 1904, 1915) and Alabama (Walker, 

 1928). It is probable that additional species of Mollusca will be 

 found in Indiana, bringing the number of species and races ot 

 that state to approximately the total of those in Illinois. 



Comparisons of two genera, Polygyra and Gastrocopta^ show 

 the large Illinoian fauna of these important groups. Table 1 

 compares graphically the total land snail fauna, the polygyras 

 and the gastrocoptas of the six states in which the Mollusca 

 have been most carefully studied. Alabama alone exceeds Illinois 

 in the number of species represented. 



Table 1. — Total number of species, subspecies, races and vari- 

 eties of Mollusca and of two important genera reported from six 

 states. 



State 



Total 

 Number 



Polygyra 



Gastrocc 



ipta 



Authority 



Date 



Illinois 



122 



34 



13 





Baker 



1939 



Michigan 



103 



23 



8 





Winslow 



1926 



Indiana 



100 



28 



5 





Daniels 



1915 



Ohio 



105 



22 



8 





Sterki 



1907 



Pennsylvania 



102 



22 



5 





Brooks 



1931 



Alabama 



185 



58 



14 





Walker 



1928 



It is possible that a few additional species may be found to 

 inhabit Illinois, especially the northern portion bordering Wis- 

 consin and the eastern adjoining Indiana. 



