POSTGLACIAL BIOTA OF THE GREAT LAKES REGION 193 



migration also from the southeast, possibly by way of the Mohawk-Trent 

 outlet (Plate LII), at which time certain species characteristic of the Atlantic 

 fauna migrated into the Huron basin and have now reached as far westward as 

 eastern Lake Superior and the Upper Peninsula of Michigan. Elliptic* com- 

 planatus, a member of the Atlantic fauna, is found as a fossil as far west as 

 Simcoe District, Ontario (town of Angus). 



The two faunas, the Mississippi Valley and the Atlantic coastal plain, as 

 represented by fossil examples, may be tabulated as follows. The Atlantic 

 fauna invaded the territory north and east of Lake Superior, the Lake Huron 

 region, a portion of the Northern Peninsula of Michigan and the territory east 

 of central New York. 



Mississippi Valley Atlantic Coast 



Fusconaja undata 



" solida 



Crenodonta peruviana 



undulata 



Quadrula pustulosa 



'. pustulosa sclwolcraftensis 



" lachrymosa 



Rotundaria tubercidata 



Pleurobema coccineum 



coccineum magnalacustris 



FJliptio crassidens 



" gibbosus 



_ FJliptio camplanatus 



Symphynota cotnpressa 



" costata 



Anodonta grandis : 



" grandis footiana 



" marginata Anodonta marginata 



" calaracta 



Anodontoides subcylindraceus ..., 



Alasmidonta marginata 



calceola _ 



Obovaria circula 



" ellipsis 



Obliquaria refiexa 



Amygdalonajas elegans 



Propter a alala 



Eurynia iris , 



" ellipsiformis 



recta , 



Lampsilis luteola Lampsilis radiata 



" ventricosa *. 



" anodontoides 



