The list of Margaritinae remains unchanged. 

 For the purposes of this paper, therefore, the total num- 

 ber of species recognized is sixty-one, divided as follows: 



Unio, 40 



Margaritina, 5 



Anodonta 16 



61 



A full list of these and of those considered doubtful and 

 synonymous will be found in appendix I. 



Of each of these species a list of localities has been com- 

 piled from the reports above mentioned and these again have 

 been spread upon an outline map of the state prepared for the 

 purpose and showing the principal rivers and lakes. By this 

 means the range of each species over the state is shown in 

 connection with the principal drainage systems in such a way 

 that at a glance the relations, if any, between the two are 

 obvious. An examination of these maps will show that 

 there is a great difference in the range of the various species. 

 Some appear to be of general distribution all over the state; 

 others are confined to the northern part; while others are 

 apparently restricted to the more southern streams; while 

 still others seem to be limited to much smaller districts. 



On collating the species, which seem to have substan- 

 tially the same range, and considering each genus separately, 

 we find the following results. 



UNIO. 



Of the forty species of this genus, but seven appear to 

 range over the whole state, viz: 



I in'o gibbosus Bar. 

 luteolus Lam. 

 nasutus Sav. 

 novi-eboraci Lea. 

 p/iascolus Hild. 

 ftressus Lea. 

 ventricosus Bar. 



Three species are peculiar to the northern part of the 

 state, viz: 



Unio borcalis Gray. 

 complanatus Sol. 

 superiorensis Marsh. 



