1922] Peattie,— Coastal Plain Element in Flora of Great Lakes 83 
kee River in Indiana, only some thirty miles south of the old Lake 
Chicago Basin. The Kankakee itself flows through the site of an 
old glacial Jake bed. But this glacial lake drained into the Mississippi 
Basin and not into Lake Chicago, and as Mikania scandens is not 
found on the Great Lakes, although extending by way of the Mohawk 
and Hudson to the Ontario Basin, it is best treated as a plant of the 
southern coastal plain reaching a northern limit in Indiana, and not 
one of the migrants of the Great Lakes. Another coastal plain and 
piedmont plant reaching a northern limit on the Kankakee is Betula 
nigra, and there are others of the same sort. 
THe NEGATIVE EVIDENCE. 
There is a certain amount of negative evidence in favor of the 
glacial lakes as a pathway of migration for coastal plain plants. In 
the first place, we know only a single coastal plain species! on the 
Great Lakes which is not also found fairly far north on the true coastal 
plain—far enough north for it to have migrated by way of the New 
York State connectives with the glacial lakes. In other words, coastal 
plain plants ranging from the Gulf around Florida to about the lat- 
itude of Delaware, but not northward, are almost wholly absent from 
the Great Lakes, though they may often reach far up the Mississippi 
Basin and be found in southern Illinois, Indiana or Ohio. Such a 
range have Styrax americana, Taxodium distichum, Jussiaea decurrens, 
Spigelia marilandica, and many others. It is evident, therefore, 
that few, if any, of the coastal plain plants of our area have come by 
way of the Mississsippi Basin. 
And in the second place, there is the flora of the sand hills of Ne- 
braska, with which there has never been any glacial lake connective 
which could be satisfactorily demonstrated. And we have already 
seen that not a single true coastal plain species exists there. 
THE ZOOLOGICAL EVIDENCE. 
There is a little zoological evidence which is corroborative of that 
of the plants. Animals, being free-moving organisms, are in general 
less restricted in their ranges than plants. But there are a few animals 
ordinarily confined to the coastal plain which are isolated in the area 
1 Eleocharis caribaea (capitata) var. dispar, which is an endemic of the Lake Mich- 
igan region, derived from true E. caribaea, a plant not known on the coastal plain 
north of Maryland, though further investigations may give it a station far enough 
north to displace it as an exception to the rule. 
