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considerable space on the eastern side above the mansion 
and below the boulder bridge. The area west of the river 
extends from just above this bridge down stream to a 
point nearly opposite the old Lorillard snuff-mill, and is 
the part commonly designated “Hemlock Grove.’ Its 
total length along the river is approximately 3,000 feet; its 
greatest width, goo feet, is at a point on the river heat 
700 feet above the ae at the mansion. The total 
area occupied by the trees on both sides of the river is be- 
tween thirty-five and forty acres. 
While this area is mostly covered by the hemlock spruce, 
and although they form its predominant vegetation, other 
trees are by no means lacking; beech, ash, sweet birch, 
red maple, hickories, oaks, dogwood, tulip-tree and other 
trees occur, and their fcliaee protects the hemlocks from the 
sun in summer to a very considerable extent; there are no 
coniferous trees other than the hemlock, ioweven within 
the forest proper. The shade is too dense for the existence 
of much low vegetation, and this is also unable to grow at all 
vigorously in the soil formed largely of the decaying resi- 
nous hemlock leaves; it is only in open places left by the 
occasional uprooting of a tree or trees by gales that we see 
any considerable number of shrubs or herbaceous plants, 
their seeds brought into the forest by wind or by birds. In 
fact, the floor of the forest is characteristically devoid of 
vegetation, a feature shown by other forests of hemlock 
situated further north. The contrast in passing from the 
hemlock woods to the contiguous hardwood area which 
borders them to the west and north, toward the museum 
building and the herbaceous grounds, is at once apparent, 
for here we see a luxuriant growth of shrubs and of herbs, 
including many of our most interesting wild flowers. 
21. The Gorge of the Bronx River 
The gorge of the Bronx River extends from the boulder 
bridge at the north end of the hemlock forest southward 
for about a mile, nearly to Pelham Avenue, and is a most 
