walker: shells of MICHIGAN. 325 



Alluvium of river Garonne contained 60 species out of 

 the 140 living in the environs or 0.42. 



One being 5/1 1 and the other 3/7. In fact there is scarcely 

 any difference between the amounts of the two. 



This study of the alluvium enables the conchologist to get in 

 a very short time a pretty good notion of the fauna of the surround- 

 ing district, and I am convinced that many new species will yet be 

 found in that manner, which may have been overlooked by the 

 ordinary way of searching. 



As regards the genus Pupa I found 14 different species in this 

 years alluvium at Bordeaux, which have been classified by Dr. 

 Boettger, one of the greatest living authorities on ClausilicB 

 and Pupa. 



In concluding this short paper, I hope, that if any new species 

 should be discovered in English alluvia, it may be by some 

 member of our " Conchological Society." 



CATALOGUE OF THE SHELL-BEARING MOLLUSCA 

 OF MICHIGAN. 



By BRYANT WALKER. 



The following list of the land and freshwater shells of the 

 state of Michigan embodies not only the results of my own 

 collecting during several years past, but also the various catalogues 

 heretofore published, and such scattered references as occur in 

 the various scientific publications to which I have had access, and 

 is intended to furnish as completely as possible a summary of our 

 present knowledge of the fauna of the state. 



Up to this time there have been published three general lists 



