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a matter of pure speculation whether any vegetation persisted 
during the Pleistocene on Long Island or not, but evidence seems 
to point to the negative probability. If this is true then all of 
the New Jersey flora now found on Long Island must have had 
a post glacial origin. The distribution of Pinus echinata, P. 
virginiana and the red squirrel may throw some light on the post- 
glacial chronology of events on Lond Island. Both these pines 
are found in the region surrounding the pine-barrens, but are 
unknown, or very rare in them. Pinus rigida the predominant 
tree of the barrens is common on Long Island, but the two 
pines mentioned above and the red squirrel are not known on 
the island. From the geological outline given above we know 
that P. virginiana and P. echinata must have occupied the region 
surrounding the pine-barrens long after the last effects of the ice 
were past. This may also have been true of the red squirrel. 
At any rate, after a large post-glacial migration of alleged '' pine- 
barren" plants, the avenue of migration must have been broken. 
The discontinuance of this passageway must, it seems to me, have 
been the controlling factor in the failure of Pinus echinata, 
P. virginiana and the red squirrel to reach Long Island. It is 
curious in this connection that both the pines, but not the 
animal, are found on Staten Island. The geological events 
causing this very decided cut-off are outside the scope of this 
paper. It may, however, have been something other than geo- 
logical phenomena operating here. There are, of course, many 
more species than these pines, which apparently reach their 
northern distribution point in the region surrounding Beacon · 
Hill, or in Staten Island, never having been reported from Long 
Island. It seems probable that they came northward in post 
glacial times, too late to avail themselves of the already destroyed 
avenue of migration. 
One other extra-territorial occurrence of pine-barren species 
should be noted. A widely quoted paper of Britton's? is often 
cited in support of the theory that pine-barren plants are not 
2 The reported occurrence of Pinus virginiana in Suffolk Co., L.II., by Miller and 
Young cannot be verified. It was probably a misdetermination of P. rigida. 
tains of northwestern New Jersey. Bull. Torrey Club 11: 126-128. 
