Baker—Malluscan Fauna of Tomahawk Luke, Wisconsin . 218 
MOLLUSCA COLLECTED. 
Anodonta grandis footiana. 
Anodonta marginata. 
Planorbis binneyi. 
Planorbis campanulatus. 
Lymnoea stagnalis lilliance. 
Station XV. (Figure 10.) 
Swampy pond at Sanders’ “minnow-box,” north side of lake,, 
near Sanders’ .Resort. This station has been artificially pro¬ 
duced by damming a little creek which flows from a small lake 
north of the Northwestern Railroad embankment. This barrier 
has caused the formantion of a shallow, stagnant pond, from, six 
inches to about four feet in depth. The bottom is now very 
muddy, although originally hard and firm, showing the rapid 
decay and acumulation of plant humus. The water is thickly 
filled with Chara and the surface with Spirogyra. A large 
amount of duckweed (Spirodela) is scattered over the surface, 
as well as a species of Lemna. The trees surrounding this pond 
are nearly all second growth and embrace birch, oak, elm and 
poplar. The photograph shows a number of dead bushes, killed 
by the rising of the water. 
Mollusks were common either swimming near the surface or 
crawling over the bottom. The vegetation on the surface of the 
pond was so thick that it was necessary to clear a patch of water 
before the mollusks could be seen. Planorbis was more fre¬ 
quently seen on the bottom, while Lymnasa seemed to prefer 
sticks or old logs in the water, or the vegetation. Physa was 
observed on the bottom or on logs, while Musculium was found 
only in the vegetation. Segmentina was seen only on logs and 
sticks. 
