Of these the first and last are variations of the common 

 luieolus stock, so abundantly distributed throughout the state. 



Unto complanatus has recently been ascertained to exist 

 in Macomb, Monroe and Lenawee counties, in the southeast- 

 ern part of the state, and at Muskegon on the west shore. It 

 is essentially a northern species, however, and unless further 

 observations shall increase its southern range, it can scarcely 

 be considered a species of general distribution. 



A few species have thus far been found only in Lake 

 Erie, the Detroit river and the streams tributary to them. 



They are 



Unto Jabalis Lea. 



liippopceus Lea. 

 leibii Ler. 

 multiradiatus Lea. 

 rangianus Lea. 

 sulcatus Lea. 



The range of the remaining thirty-four species belonging 

 to our fauna is apparently bounded on the north, roughly 

 speaking, by line drawn diagonally across the state from the 

 mouth of the Saginaw river to the mouth of the Grand river. 



Of these, three species have been found only in the Grand 



river, viz: 



Unio Icevissimus Lea. 

 kirtlatidianus Lea. 

 tenuissimus Lea. 

 Two others appear only in the Grand river on the west 

 side of the state and near the mouth of the Saginaw river on 

 the east coast. 



Unio asperrimus Lea. 1 

 cornutus Bar. 

 Most of the remainder of this group appear to have a 

 general range around the entire southern part of the state. 

 A considerable number, however, have not yet been reported 

 from the interior of the state, viz: 



Unto alatus Say. 

 cir cidas Lea. 

 donaciformis Lea. 

 etegans Lea. 

 ellipsis Lea. 

 gians Lea. 

 gracilis Bar. 



i Siuce this was written, a single valve of this species has been found on the shore 

 of Belle Isle, Detroit River. 



