80 



NEW YJEK STATE MUSEUM 



The following interesting note concerning this species is taken 

 from a paper by Charles T. Simpson, published in the proceedings 

 of the U. S. National Museum, p. 593, 1893 : 



" It is an oriental species, having its metropolis in northern Europe 

 and Asia, which has crossed over into North America in all probability 

 by a now submerged landway, and to-day is found in British Columbia, 

 Washington, Oregon, Northern California, and in the upper waters of 

 the Missouri. It is agaiu met with in Eastern Canada, New England, 

 Pennsylvania and New York, but has not been reported from any of 

 the iutervening territory. The suggestion made several years ago by 

 Prof. A. G. Witherby, that it had been destroyed in this region by 

 glacial action, seems the most reasonable, and it is possible that at the 

 eastern side of the continent it might have survived in the area not 

 covered by the ice cap or that it may have been driven to the south 

 ward before it. 



" This is the only naiad now found living within the Mississippi 

 drainage area that may be said to belong to the Atlantic system, and it 

 is undoubtedly an immigrant. It probably entered the Missouri 

 through streams which connected that river with the northwestern lake 

 sy&tem " 



Margaritana Marginata, Say. 



Maine. 



Morse. 



Rhode Island. 



New York. 



Hudson river system 



Oak Creek, Otsego county 



Seneca river 



Chemung river , 



Tioga river 



Canandaigua lake 



Allegheny river, Olean 



Ontario. 

 Ottawa 



Pennsylvania. 



Philadelphia 



Allegheny river, Warren county 



Ohio. 



Ohio river system 



Carpenter. 



Morgan. 



Beecher. 



Walker. 



Wright. 



Wright. 



Pickett coll. 



Latchford. 



Coll. Phila. Acad. 

 Beecher. 



Sterki. 



