398 Wisconsin Academy of Sciences, Arts, and Letters. 
Epicordulia princeps (Hagen). 
In parts of the lake, especially opposite rocky shores, the lar¬ 
vae of this form are not at all scarce. During July one may 
see the exuviae clinging to the face of the cliff for a height of 
10 meters, while the spotted adults are busily engaged hunt¬ 
ing for prey or ovipositing. The eggs are laid in long strings, 
usually at the surface on the floral beds of Potamogeton and 
other plants. 
D. Order Hemiptera. (Table 5, p. 475). 
Hemiptera are not conspicuous in the lake community. Few 
of them are hardy enough to withstand the severities of lake 
conditions. Two species of Corixa, one of Notonecta and of 
Pelocoris, and the ubiquitous Plea striola form the Hemipteran 
contingent of the lake; and for the first three it must be noted 
that they are abundant only in the tiny nooks one may find 
along the shore line, where the immediate shore forms an ac¬ 
cessible shelter during adverse conditions. 
Experiments have shown that Corixa cannot endure any 
prolonged submersion in disturbed water, two hours being 
the maximum; Notonecta is a little more hardy, while the 
minute Plea is hardiest of all, enduring a submergence of five 
hours without much damage. That the true habitat of all five 
of these species is not the lake, is indicated by the fact that 
in flowing streams, and especially in the swamps of the Yahara 
River, the same species of Corixa, Notonecta, and Pelocoris are 
enormously abundant, at least three times as abundant as in 
the most favored spots of the lake. Pish caught in such re¬ 
gions will be found gorged with specimens of one or all species. 
Belostoma, Nepa, and Ranatra are entirely absent from the 
lake. They are adapted to an emergent or floating vegetation 
and hence do not occur in the lake. Only the fact that Noto¬ 
necta, Corixa, etc. may rapidly change from an aquatic me¬ 
dium to the shore permits them to stay in the lake, but then 
always within a short distance of the shore, as indicated by 
the quantitative hauls. 
E. Order Neuroptera. 
Sysira umbrata Needham. 
This is the only spongilla fly I found in the lake. At Maple 
Bluff it is occasional in the encrusting sponges. No numerical 
