24 SOUTH AMERICAN TIPULIDAE 
diverge from R3 is apparent. The genitalia of the male 
sex shows several distinct lines of specialization. The general- 
ized jivaro and exilis have the ninth tergite large, subquadrate, 
with a broad and deep median furrow; the ninth pleurite is 
extensive, the eighth sternite very small but with a conspicuous 
median tripartite organ. As evolution proceeds we find the 
broad furrow on the ninth tergite narrowed to a delicate impressed 
line, the ninth pleurite becoming small, oval or elongate-oval, 
situated on the caudal face of the ninth sternite and the eighth 
sternite with the median lobe single and finally becoming re- 
duced to a mere tuft of hairs. The order of specialization in 
the forms known to me seems to be about as follows: 
1. More generalized with shortened antennae and generalized 
hypopygiuniy — jivaro, exilis and possibly other species described 
by earlier workers, but from their insufficient descriptions not 
definitely recognized. 
2. No representatives of the intermediate group are known to 
me. 
3. With the antennae elongated but still much shorter than the 
body, — mitua, ornaticornis V. d. W., carizona Alex. 
4. Highly specialized species with the antennae only a little 
shorter than the entire body, — monilifera Loew, moniliformis 
Rod., armillatus. Of uncertain position, known only from 
the female sex, — quichua sp. n. 
The body color-pattern is curious and is indicated in all of the 
species. The insects show a more or less distinct, very narrow, 
dorso-median vitta running from the head over the entire length 
of the thorax; on the ground color between the usual thoracic 
stripes occur rather abundant hair-like setae and each of the 
setigerous punctures is surrounded by a brown circle, producmg 
a spotted appearance. 
Tipula exilis sp. n. 
Monilifera group; antennae short in both sexes; head and thorax dark gray; 
a narrow dorso-median line running the length of the thorax; wings mottled 
white, brown and gray; abdomen of the female very long and slender. 
Male.-rLength, 12 to 15 mm.; wing, 12.1 to 14.1 mm.; abdomen, 11.6 mm. 
Female. — Length, 24 to 26 mm.; wing, 15.2 to 15.5 mm.; abdomen, 19 to 
21.5 mm. 
Frontal prolongation of the head moderately long, brown, a little darker 
on the sides of the organ; palpi moderately long, dark brown. Antennae 
rather short (see plate IV, fig. 5), a little longer than in 7\ jivaro which is very 
