481 
summer and fall. Under these leaves Aplexa hypnorum is very 
abundant. The bordering vegetation is the same as that surround- 
ing the pools mentioned under Station XXXII. 
The following mollusks were observed: 
Aplexa hypnorum. Common. 
Succinea avara. Rare. 
STATION XXXII. 
(Plates X XID, XXI11., and X<KIV.,1.) 
A pond about three hundred by one hundred feet, situated on 
the edge of a rather dense forest of American elm, shellbark hickory 
and swamp white oak trees. The pond is bordered on the north by 
the heavy forest, on the east by the open forest, on the west by a 
steep ridge and on the south by an open field. Unlike the ponds 
previously considered, the aquatic vegetation is scant and confined 
to a few scattering Iris at the north end. The bottom of the pond 
is composed of sticky blue clay. The pond is very interesting, lying, 
as it does, at the very base of the steep ridge and differing so mark- 
edly from the other ponds of this region in the almost total absence 
of cattails (Typha) and other reeds. Plate XXII. shows its loca- 
tion at the base of the ridge and Plate XXIV., 1, shows its condition 
in September after a prolonged period of drouth. In the early 
spring, the water extends to the trunks of the trees, as shown in 
Plate XXIII., which was, however, photographed in September, 
1909. Comparison between this plate and Plate XXIV., 1, will 
illustrate the effect of a dry and a wet season on the ponds and 
pools in this area. 
Only a few species of mollusks were observed in the pond. 
At the north end, under wet leaves, in a low area subject to 
inundation, Ancylus parallelus was found in considerable numbers 
attached to the under surface of the dead leaves. 
The following species of trees were noted about the pond: 
Carya ovata. Shellbark Hickory. 
Populus tremuloides. American Aspen. 
Quercus bicolor. Swamp White Oak. 
Quercus rubra. Red Oak. 
Ulmus americana. American Elm. 
Tilia americana. American Basswood. 
Acer saccharum. Rock Maple. 
Salix longifolia. River-bank Willow (in pond). 
