AQUATIC INSECTS IN NEW YORK STATE 437 



both European species. The genus belongs to the group Chiron- 

 omus {sens, kit.); but differs from all the other genera of this 

 group in having the fourth tarsal joint shorter than the fifth 

 [fig.l4], resembling in this respect Tanjpus, 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 fuscons, 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 I4th. Dorsum of the thorax 

 blackish. Yellow on the humeri and pleura, covered with a 

 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 

 on 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 hj^aline, hairless, the an- 

 terior veins yellowish, the rest hyaline; venation as in the figure; 

 anterior and posterior margin delicately ciliate; genitalia in- 

 conspicuous [fig.l3, 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, 



