240 
barren flora contributes some data that support the views out- 
lined above. Particularly the finding of Xerophyllum, Helonias, 
and Oceanorus, to mention only a few, on the mountains of 
eastern Tennessee, is of interest. These and many more were 
found by Kearney? and more recently by Small, in geologically 
the most ancient area in America (Archaean). The hiatus in 
the distribution of these plants between the pine-barrens and 
these very old mountains is easily explainable by the isolation 
theory above advocated. The fact that they are wanting or 
very rare in the intervening territory would seem to present 
strong evidence of the unavailableness of this intermediary area 
(most of it was under water), during the geological changes 
described above, for the perpetuation of the species now so far 
isolated. Furthermore this southern isolation strongly favors 
the statement made above that most of the pine-barren flora was 
of southern extraction, for it is quite reasonable that the species 
found on the Tennessee mountains and in the pine-barrens of 
New Jersey are simply relicts of an ancient American southern 
flora that must, at one time, have covered a vastly greater area 
than it does to-day. The present nearly complete isolation and 
the post-glacial distribution of this southern flora, both it seems 
to me, favor this view. 
There remains still to be considered the " pine-barren"' plants 
of Long Island and Staten Island, not to mention regions further 
east. As Stone has shown a good many of these alleged “ріпе- 
barren" plants are only coastal plain plants? which are found, 
it is true, in the pine-barrens; but more commonly in the area 
surrounding them, frequently throughout the Atlantic seaboard 
from Massachusetts to Florida. It should be remembered in 
this connection that neither Long Island nor Staten Island are 
in the same geological category as Beacon Hill. For both the 
former were in part covered by the glacier and both were more 
or less within the influence of glacial activity. It is, of course, 
29 The pine-barren flora in the East-Tennessee Mountains. Plant World 1: 
33-35. 1897. 
30 Stone, W. loc. cit. 73 
91 Long Island was not covered wholly by glacial drift, but the sandy plain south 
of the moraine received considerable overwash material, now mixed with the 
underlying Tertiary sand and gravel. 
