Muttkowski—The Fauna of Lake Mendota. 
411 
(ammophilous), and is common on sand beaches and in the 
finer gravel. C. fulviventris is somewhat similar in its pre¬ 
dilections, but more isolated in its distribution. C. lobiferus 
is quite regular in its distributon, and is a ubiquist as regards 
its habitats,—varying from sand, gravel, and rocks, to plants 
and filamentous algae. 
The larvae of the three species are trimorphic as to color. 
The larva of C. lobiferus may be a bright red, a very pale 
green, or reddish transfused with green. In C. fulviventris 
bright red larvae occur, others that are pale cream, olive green, 
or red with a transfusion of green. Even more marked are 
the distinctions of C. digitatus in which a scarlet larva is com¬ 
monest, white or pale green next frequent, and a rarer form is 
colored a dark red with green parenthetical dorsal markings 
on each segment. I have tried to discover a racial character 
in these markings, but the breedings of all three types for C. 
digitatus and C. lobiferus proved their identity. 
A peculiar feature is that in C. digitatus and lobiferus the 
variations occur side by side, so that one may find red and 
green forms of either species in the same locality. In C. ful¬ 
viventris I have found the red forms only in the short rapids 
of Merril Spring and in the sandy parts of the lake shore; the 
pale cream form seems to be confined to the outlet of Univer¬ 
sity Brook into University Bay. 
The food of these three species has been examined in sev¬ 
eral hundred specimens. Diatoms, Protozoa, algal spores, and 
in several instances smaller Chironomid larvae, were found in 
the stomachs. On two occasions larvae of Hydrachnida were 
found in C. lobiferus; these probably belonged to Limnesia 
histrionica, for those of other species are less common and 
generally protected by armor or secretions. In turn, the lar¬ 
vae are eaten by fish; C. digitatus notably forms the food of 
shore fishes, especially of the darters, and Cottus. I have seen 
smaller larvae frequently attacked by Hydrachnids, while the 
crustacean Hyalella azteca at times has the annoying habit of 
nibbling at the respiratory tufts of the pupae (field and labor¬ 
atory observation). 
Chironomus plumosus Linne; Chironomus tentans var. 
Both species are confined to the littoral area. C. plumosus 
in Lake Mendota is restricted to a few places on the north 
