AQUATIC INSECTS IN NEW YORK STATE 437 
both European species. The genus belongs to the group Chiron- 
omus (sens. lat.); but differs from all the other genera of this 
group in having the fourth tarsal joint shorter than the fifth 
[fig.14], resembling in this respect Tanypus, and Diamesa, from 
which it differs in the wing venation; the R—M cross vein want- 
ing; antennae as in Chironomus. 
T. obscura n. sp. 
This fly was very common here during the past summer, the 
larva living on the rocky bottom of the shallow, swiftly flowing 
streams, where the water is but an inch or two in depth 
[pl.32], sometimes in company with Simulium; it spins a 
loose cocoon so open and transparent that the larva is not hid- 
den by it, though it prevents the larva from being washed away. 
Male. Front and epistome yellow, palpi fuscous, shorter than 
the antennae, its first joint about one and one half times as long 
as broad, the second twice, the third three times and the fourth 
about four times as long as the first. Antennae fuscous, 14 
jointed, the first disklike, the second longer than broad, the third 
to the 13th about as long as broad, the 14th longer than all the 
others taken together; all furnished with long brown hairs ex- 
cept the apical one fourth of the 14th. Dorsum of the thorax 
blackish. Yellow on the humeri and pleura, covered witha 
white bloom, most conspicuous on the humeri. The dorsum of 
the thorax has a dirty yellow ground color but the three black 
longitudinal stripes are so wide that only a little of the ground 
color shows, excepting on the humeri and the two very narrow 
faint longitudinal stripes separating the three wide, black ones. 
The scutellum is chestnut; metathorax black; pectus brown; 
abdomen dull black, the dorsum of the first two segments 
greenish; the extreme edge of each segment, paler fuscous; the 
venter greenish, darker, almost black on the more posterior seg- 
ments. The green is sharply separated from the dorsal color 
en a lateral line. In dried specimens this green color becomes 
dusky. Legs almost black, the coxae and bases of the femora 
yellowish, tarsal claws simple; wings hyaline, hairless, the an- 
terior veins yellowish, the rest hyaline; venation as in the figure; 
anterior and posterior margin delicately ciliate; genitalia in- 
conspicuous [fig.13, dorsal view].  Halteres white. Length 
3 to 5 mm. 
Female. Antennae seven jointed, black, with short hairs. 
Thorax with the black stripes a little narrower than in the male, 
