TRIMICRA. 165 



species ; the marginal cross-vein is almost on one line with the 

 inner end of the first submarginal cell ; the latter is but very 

 little anterior to the inner end of the second submarginal and 

 first posterior cells ; the third posterior cell is much shorter than 

 the first (the venation can of course be perceived only when the 

 hairs are rubbed off). 



Hab. Washington, D. C, and Maryland ; forms clouds in the 

 spring near running waters. This species seems to be very like 

 the European E. murina Meig. ; but I have had no opportunity 

 for a comparison. 



Gen. XVIII. TRIMICRA. 



Two submarginal cells ; four posterior cells ; a discal cell ; the second 

 longitudinal vein originates, at a more or less acute angle, before the 

 middle of the length of the wing and a considerable distance (more than 

 the breadth of the wing) before the tip of the auxiliary vein ; the sub- 

 costal cross-vein is at a considerable distance (three lengths of the great 

 cross-vein, or more) from the tip of the auxiliary vein ; seventh longi- 

 tudinal vein straight. Wings and their veins glabrous (Tab. II, fig. 1). 

 Antennae 16 -jointed; three last joints of the flagellum abruptly smaller. Tibiae 

 without spurs at the tip ; ungues small, smooth on the under side, inserted 

 under a projection of the last tarsal joint ; empodia small, but distinct. 

 Forceps of the male with large, incrassated basal pieces, and a double 

 claw-shaped horny appendage fastened to them on each side ; ovipositor 

 with flattened, curved, pointed upper valves and short lower ones. 



Rostrum and palpi short ; eyes glabrous, separated above by a 

 moderately broad front and almost contiguous below. Antennae 

 of moderate length, or rather short, as they would hardly reach 

 the root of the wings, if bent backwards ; joints of the flagellum, 

 especially the basal ones, short, oblong or subcylindrical, with 

 moderate verticils ; the three last joints of the antennae are 

 abruptly smaller than the preceding ones (this peculiarity may 

 be perceived even in dry specimens). Feet comparatively long, 

 more or less clothed with hair, sometimes conspicuously hairy ; 

 intermediate pair comparatively short; femora sometimes con-. 

 spicuously incrassated at the tip. The position of the ungues 

 under a projection of the last tarsal joint, which likewise exists 

 in some degree in Erioptera and Symplecta, is particularly strik- 

 ing here. The forceps has very stout basal pieces, closely applied 

 to each other (and not w r ith an open interval between them, as in 

 Symplecta). The wings (Tab. II, fig. 1) are rather long and 



