36 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



black, paler at the base; thorax wide, subquadrate. slightly convex, black, with 

 a grayish reflection, and golden scales; humeri pale; pleurte black, anteriorly 

 and posteriorly, with fuscous spots; scutellum fuscous; halteres white; abdomen 

 black, base of second segment pale yellowish on the sides ; fore and middle coxae 

 wholly yellow, hind ones fuscous, with yellow tips; fore femora wholly yellow, 

 mid and hind pairs fuscous-black, with yellow bases; fore tarsi wholly black; 

 middle tarsi black, with bases of all the joints yellow; hind tarsi black, with 

 base of first joint broadly and of second joint narrowly yellow ; wings hyaline, 

 iridescent. Length 4 mm., alar expanse 9 mm. 



Simulium parnassum, new species. 



FemoXe. — Black, slightly shining; prescntiim paler; pleiirac pale 

 along the sutures; abdomen opaque black on basal four segments, 

 shining on apical four; legs black, yellowish as follows: Coxse, tro- 

 chanters, bases of tibise, and base of first joint of tarsi of fore legs; 

 apices of coxa?, bases of trochanters, bases of femora, of tibiae 

 narrowly, and of first tarsal joint of mid legs; trochanters, bases of 

 femora and of tibia*, basal two-thirds of first and basal half of sec- 

 ond joint of hind legs. Halteres yellow, stalk dusky at base. 



Frons glossy black, sides divergent, about one-third wider at vertex 

 than above antenna;, surface hairs strong, upright, black, present 

 only on lateral margins, especially toward vertex, absent from 

 center; face distinctly longer than broad (1-^:1), grayish pollinose, 

 almost bare on center, with long hairs on lateral and lower margins : 

 antenna? brown, the basal two joints and base of third generally 

 paler; second and third joints elongated, subequal, as long as 4-|-5; 

 pilosity short, thick, pale; palpi black-brown, black haired; post- 

 ocular cilia black. Mesonotum with very slight pale pollinosity; 

 pilosity black or black-brown, close-lying, regiilar, in the depression 

 on posterior fourth the hairs much longer and upright; pronotum 

 with numerous black hairs, episternum immediately below it with 

 pale hairs; all the lower parts of pleura? with silky pollinosity; 

 pleural tuft browm-black, confined to upper fourth ; scutellum opaque 

 black, the upright hairs black, no pale hairs present. Abdominal 

 basal scale varying in color from pale yellowish to opaque black, the 

 long hairs pale brownish yellow ; membrane beneath scale generally 

 yellow; some specimens have the abdomen inclining to brown; seg- 

 ments almost bare except laterally and apically where there are 

 numerous brown hairs. Legs with close-lying pale pilosity and dis- 

 tinct, longer, upright, black hairs on the dorsal surfaces of femora, 

 tibiae, and tarsi ; the usual paired apical hairs on first and third fore 

 tarsal joints present (PI. V, fig. 11) ; hind tibitp at apices and basal 

 three-fourths of first tarsal joint of hind legs Avith short, stiff, upright, 

 golden pile; claws with tooth (see PI. II, fig. 8) ; wings clear, thick 

 veins brownish, cross-vein at two-fifths from apex of subcosta. 



Length, 2-2.5 mm. 



Type. — Cat. No. 15409, U. S. National Museum. 



