447 
such ponds were examined in this area and careful notes were made 
of their biotic contents. 
This triangular area divides naturally into three subordinate 
areas: one beside the road running at right angles with the Glencoe 
road and between this and the Northwestern Railroad cut-off; one 
west of the railroad; and one bordering the East Branch of the 
Chicago River and separated from the second area by a field about 
three hundred feet in width. The first area is a few feet above the 
Skokie Marsh stream, the second is on rising ground, and the third 
is on an elevation twenty feet above the river. A large part of the 
southern portion of this area is cleared for grazing purposes. 
C. The East Branch of the Chicago River. 
(Plates DeVille 2 and Xavi 15) 
This stream is quite wide in the spring, and is from one to six or 
more feet in depth. It occupies a little valley with a rather broad 
flood-plain flanked on either side by abrupt ridges about ten feet 
high, forming, in this part of the area, distinct terraces. The river 
meanders considerably and also varies in width and depth. The 
latter is shown plainly in the late summer, when the river is reduced 
to a succession of small, muddy pools, varying from a few inches to 
three or four feet in depth (Plate XVIII.,1). The river may be prop- 
erly termed an intermittent stream. 
The flood-plain varies in width from a few feet to two or three 
hundred feet. It is covered with swamp grass, interspersed with 
reeds in the lower places. Trees have invaded this area, and 
such species as the swamp white oak and maple are abundant on 
the broader portions, in some places forming large groves, or thick 
tangles—as where the button-bush borders the river near the south- 
ern end of the area in question. In several places the river spreads 
over the entire flood-plain, forming a characteristic bog. In most 
places, however, the river occupies little territory outside of its bed, 
except in times of very high water. 
D. Glenwood Beach Ridge. 
(Plate XXII.) 
This area lies west of the East Branch of the Chicago River, 
between this branch and the North Branch. The beach reaches 
