28 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



ments short, black-brown. Legs strong; fore tarsi compressed later- 

 all}^, basal joint as broad as tibia, joints 1-3 with paired apical hairs; 

 all legs with pale pilosit}^ and longer, upright, black dorsal hairs; 

 apical spur absent from fore tibia^, hind and mid pairs with paired 

 apical spurs; basal joint of hind tarsi as broad as tibiae, produced 

 apically on posterior surface, claws as in virgatum (PI. II, fig. 11). 

 Wings with outer two thick veins joining costa very close together 

 so that the last costal division is very indistinct. 



Length, 3-3.5 mm. 



Type and paratypes. — Cat. No. 15406, U. S. National Museum. 



Localities: Livingston, Guatemala, and Cacao, Trece Aguas, Alta 

 Vera Paz, Guatemala, April-May (Barber and Schwarz). 



Nothing is laiown of the early stages of this species. 



Simulium hippovorum, new species. 



Female. — Black, subopaque. Frons and face brownish, thickly 

 covered with white pollinosity; antennae brown, basal two joints 

 and base of third joint yellow; palpi brown. Scutum with three 

 stripes, the central one narrow, the lateral pair broader, close to the 

 central one, dilated anteriorly and slightly curved; viewed from 

 above in front the whole disk of scutum, except the stripes, is whit- 

 ish pollinose and also the prescutum; viewed from above and be- 

 hind, the anterior dilated portion of the lateral stripes is conspicu- 

 ously white pollinose; pleurae distinctly whitish pollinose except on 

 membranous portion; scutellum opaque brown; postscutum with 

 silky white pollinosity. Abdomen brown-black, opaque on basal 

 four segments, subshining on apical four. Legs yellow, black as 

 follows : Mid and hind coxae ; apices of tibiae and entire tarsi of fore 

 legs, narrowly at apices of femora; a spot at bases and broadly at 

 apices of tibiae; apices of first and from middle of second to fifth 

 joint of tarsi of mid and hind legs. Wings clear, thick veins brown. 

 Halteres yellow. 



Frons divergent-sided, at upper angle occupying one- fourth the 

 head wudth, above antennae two-thirds as wide as at upper angle, 

 surface hairs brownish yellow, sparse and weak; face broader than 

 frons at upper angle, almost subquadrate, surface hairs more numer- 

 ous than on frons, whitish; hairs on palpi pale brown; postocular 

 cilia pale, with an admixture of longer, blackish hairs on upper part 

 behind vertex. Pilosity of scutum rather loose and upright, whitish 

 yellow, hairlike, the posterior fourth with a number of longer, up- 

 right, blackish hairs; anterior pleural hairs pale and hairlike, close 

 to lateral margin of scutum; pleural tuft pale, confined to upper 

 fourth, j)ostspiracular area pale haired. Abdominal basal fringe 

 pale yellow ; surface hairs on segments sparse, pale. Legs with yel- 

 low, close-lying pilosity and longer, upright, black dorsal hairs; 

 fore tarsi not noticeably thickened, the paired apical hairs present 



