1915] 
Cahn: Ecology of Wingra Springs Region 
129 
The Springs 
The springs fall into two groups, the three at the shore of 
the lake, and the one spring rising about half a mile south of 
the lake, and flowing to it through the center of the formation 
in the shape of a small, slow-moving stream. Of the three 
springs, the third, or westerly one, is the largest during the 
greater part of the year; and others, though they are an attrac- 
tion to birds, are always subordinate in importance to the larger 
one. These springs rise at the very edge of the woods, where 
they bubble forth from among small stones. All three are for 
the most part shallow, though the bottom is soft in the extreme, 
and offers very unstable footing. 
The basins in which these springs first appear are in every 
case free from vegetation, as is the channel for some yards 
from the rise. The dominant plant in all three is water-cress 
( Radicula nasturtium-aquaticum ) , and this grows luxuriantly 
in large beds at intervals in the course. These beds are of great 
importance to many species of birds (rails and various sandpipers 
in particular) . Among the roots swarm innumerable amphipods, 
mostly Dikerogammarus fasciatus and the smaller Hyalella azteca 
upon which these long-legged birds feed, their spread of the 
toes allowing them to stand or run upon the surface without 
going through. The larva of the caddice-fly Limnephilus rhornbi- 
cus is found here in abundance; and when found without their 
cases the larvae frequently serve as food to any birds frequenting 
the cress beds (6). Many small fish ( Notropis heterodon, Umbra 
limi, and, nearer the lake, Eupomotis gibbosus) follow very 
closely the general distribution of fish in a small stream as 
outlined by Shelford (19). In the basin where the springs 
take their rise the dominant forms are Dikerogammarus faciatus , 
the isopod Asellus communis , and the caddice-fly larva Platy - 
phylax designatus. Physa gyrina abound on the rocks and 
stones. 
The stream which flows through the formation, though it 
drains quite a definite area, has no definite source; it takes its 
origin somewhere in a small swamp of about three acres in 
extent, and is not well defined until it begins its flow in a worn 
channel at the edge of the woods, flowing in a north-easterly 
