DICRANOTA. 281 ' 



eyes, the position of the subcostal cross-vein, etc., and assigning 

 it its true place among the Amalopina (Pediciformia, olim). 

 The name of the genus is derived from SLxpavov, fork. 



Description of the species. 



1. 15. rivularis 0. S. % and 9 • — Obscure cinerea, thorace vittis 

 fuscis ; halteribus pallidis ; antermis maris brevibus ; cellulis posteri- 

 oribus quatuor. 



Dark gray, thorax with brown stripes, halteres pale ; antennae of the male 



short ; four posterior cells. Long. corp. 0.'28 — 0.3. 

 Syn. Dicranota rivularis 0. Sacken, Proc. Ac. Nat. Sc. Phil. 1859, p. 249. 



Head dark yellowish-gray, front and vertex slightly brownish ; 

 rostrum, palpi, and antenna? blackish ; the latter short in both 

 sexes, not reaching the base of the wings ; joints of the flagellum 

 subglobular. Thorax dark gray, with three distinct blackish- 

 brown stripes ; the intermediate one broad, and, in some speci- 

 mens, distinctly divided by a longitudinal paler line ; scutellum 

 and metathorax dark gray, the posterior half of the latter black- 

 ish ; halteres pale ; coxae gray, feet blackish, trochanters and 

 basis of the femora paler. Abdomen blackish cinereous, indis- 

 tinctly whitish along the lateral margins ; male genitals gray. 

 Wings (Tab. II, fig. 16, wing of the female) slightly tinged with 

 gray ; stigma indistinct, situated between the two marginal cross- 

 veins ; praefurca very short, and hence the distance between its 

 origin and the nearest marginal cross-vein is not longer (usually 

 shorter) than the interval between the two cross-veins. 



Hab. Washington, D. C. ; five males and two females were 

 caught, early in April, in the act of flying close to the surface of a 

 little stream in the woods ; the females were in copulation. 



One of the males has the discal cell closed on both wings ; 

 some of the specimens have a stump of a vein on the praefurca. 



2. D. eucera, n. sp. %. — Obscure cinerea, thorace vittis fuscis; 

 halteribus infuscatis ; antennae maris thorace multo longiores ; cellulis 

 posterioribus quatuor. 



Dark gray, thorax with brown stripes ; halteres with an infuscated knob ; 

 antennae of the male much longer than the thorax ; four posterior cells. 

 Long. corp. 0.26. 



"Very like the preceding species, and distinguished principally 

 by the structure of the antennae of the male, which are twice as 



