1915] 
Muttkowski: New Insect Life Histories 
121 
Halteres cream-color, triangular in form, the outer margin of the triangle 
round. 
Abdomen brown, covered with fine hair, each segment finely annulate 
with black apically. Genitalia as long as segment eight, brown in color, 
slightly marked with black, the basal joint broad, the outer joint at right 
angles to it, irregularly hastate in form. Inner process of basal joint de- 
scribing an arc, and folding into base of the segment. Dorsal keel straight, 
tapering to a point. 
$ . — Color brown and black. Head and eyes black. Palpi and antennae 
pale brown; the palpi with four joints, the antennae eight-jointed (in- 
cluding the large basal joint). 
Thorax black; scutellum prominent, hemispherical, deep-brown, with 
long setae. Legs brown, touched with black at the joint. Wings broader 
Fig. 5 Diamesa mendotae n. sp. Wing of female. Dorsal and ven- 
tral view of left male appendage. 
than in the male, longer than the abdomen, all venation brown, all mar- 
gins ciliate. 
Abdomen brown, darker on the dorsum, ciliate. Genital plates tri- 
angulate, that is, with the three corners broadly rounded. 
Length, d' 4.5 mm., $ 5 mm. 
4 Described from male and female bred October *16, 1914. These 
formed part of several dozen larvae and pupae taken at Merrrill 
Springs (Minniwakan Springs) and Merrill Creek, at the western 
end of Lake Mendota, Madison, Wis. Holotype male and allo- 
type female, and larvae, pupae, exuviae, etc., in Milwaukee Pub- 
lic Museum. 
This species is of interest in more than one respect. Ecologi- 
cally, the habitat is of interest, since the species may be ob- 
