OSTEN SACKEN ON WESTERN DIPTERA. 343 



ber of the western species which I am able to describe now, I add a 

 few interesting new species, recently discovered in the Atlantic States- 



A very striking Dejeania, very common in the Rocky Mountains of 

 Colorado, deserves to be described at once, in order to draw the atten- 

 tion of collectors to its habits. It is very remarkable that Dejeania, a 

 South American and Mexican genus, should occur so commonly at high 

 altitudes in the Rocky Mountains among alpine forms, and it would 

 be worth the while to investigate on what insect (probably Lepidopterous) 

 it preys as a parasite. 



Dejeania vexatrix n. sp., $ 9. — Head and thorax brownish-yellow; 

 abdomen bright ferruginous red, with a reddish-yellow pubescence and 

 with black spines; legs red; wings pale brownish. Length 12-13 mm 

 (exclusive of the length of the bristles, antennae, etc.). 



Face and cheeks pale yellow; cheeks with some long and sofc fulvous 

 pile; front brownish-yellow, with a brownish-red lougitudinal stripe in the 

 middle. Antennae: basal joint reddish; third joint reddish-brown; arista 

 black; palpi reddish-yellow, with short black pile. Thorax brownish-yel- 

 low, with black bristles and a shorter soft yellowish pubescence ; on the 

 dorsum, four black lines are perceptible ; the intermediate pairs diverge 

 posteriorly, and do not reach much beyond the suture ; the lateral lines 

 are broadly interrupted at the suture, and do not reach either the ante- 

 rior or the posterior margin. Scutellum nearly of the same color with 

 the thorax, with numerous black spines. Abdomen bright ferruginous 

 red, with black spines, and a shorter, dense, rufous pubescence, espe- 

 cially perceptible posteriorly ; on the first segment, under the scutellum, 

 there is a triangular black spot ; in some specimens, this spot encroaches 

 slightly upon the second segment; sometimes there are similar trian- 

 gular spots in the middle of the third and fourth segments, the spot on 

 the fourth segment being occasionally very large ; the spot on the third 

 segment is entirely wanting in the majority of my specimens.. Legs yel- 

 lowish-red, with black bristles and yellow pile on the femora. Wings 

 tinged with brownish ; the veins reddish-yellow near the base. 



Hab. — Rocky Mountains in Colorado, common. I found it very com- 

 monly about Georgetown, Colo., at an altitude of 8-9,000 feet. Among 

 the described Dejeaniw, D. rufipalpis Macq. from Mexico seems near- 

 est to it. 



Family ORTALIIXE. 



Pyrgota debilis n. sp. 2 — Brownish; wings mottled with numerous 

 pellucid spots; front yellow, tinged with brownish ; ovipositor almost of 

 equal breadth, blunt at tip. Length (including ovipositor) 7-8 mm ; wing 

 8-9 mm . 



Head pale yellow; front above the antennae with a tinge of reddish- 

 brown ; sides of front and vertex yellow, the latter with a black dot in 

 the middle ; occiput yellow, with a brown spot in the shape of a W 

 above the neck ; antenna! foveas separated by a brown ridge, which is 

 forked in front and connected with brown lines separating the sides of 



