118 Wisconsin Academy of Sciences, Arts, and Letters. 
differ more or less markedly from the same type living in the qniet 
parts of the Fox River. 
Life on Boulder Shores. All of the points facing the lake and 
all unprotected shores are covered with boulders, which form a 
typical breaker line; gravel, followed by sand, being distributed 
above the boulders (shoreward) and the same material occurring 
downward (lakeward). Typical rocky shores composed of large 
boulders seldom descend below two meters in depth. On long, ex¬ 
posed shores, as at Doemel Point, Par Rockaway Point, Asylum 
Point, and near Stony Beach, the boulders are frequently of large 
size, indicating that wave action has removed all of the finer par¬ 
ticles, leaving the heavier material as a breaker line. The typical 
boulder shore (rachion) is usually not over three meters wide on 
steep shores and descends to a depth of about a meter. Beyond 
this depth the bottom changes to coarse gravel, then to sand, and 
finally to mud. 
The plant life of this region is scanty, as would be expected, 
consisting chiefiy of filamentous algae (principally Cladophora) 
the plume-like fronds of which hang from the upper surface or 
sides of the rocks. A few emergent and submergent plants brave 
this inhospitable habitat, Scirpus occidentalis being found in one 
place, two species of Potamogeton in two places, and Vallisneria in 
another place. The last two plants occur in some abundance in 
several habitats, but Scirpus is rare. The gravel in these habitats 
made growth for these plants possible. 
Animal life is not abundant in species although certain species 
may be abundant in individuals. Among the Mollusca eleven 
species of Unionidae occur, all of them modified in form to meet 
the rigorous conditions of this unstable environment. The shells 
are smaller and thicker, on the average, than those of their river 
representatives. They are not numerous in individuals, occurring 
scattered among the boulders, between which they burrow. The 
gastropods include such species as cling to rocks and feed upon 
algae. Pleurocera, Physa, and Lymnaea are typical rock in¬ 
habitants and occur in some abundance. Planorhis parvus and 
Somatogyrus are stragglers from other shores where they live 
among the algae. All of the gastropods found on rocks (Pleuro¬ 
cera, Physa, Lymnaea) have a large, wide, ventral surface (the 
foot) which enables them to cling to the support and so prevents 
them from being dislodged by the waves. Species in this kind of 
