218 PROCEEDINGS OP THE ACADEMY OF 



clothed with black hairs ; infuscated at the tips of femora, tibiae and tarsi. 

 Abdomen fulvous, more or less infuscated ; in tf specimens the last segment is 

 generally the darkest, the forceps being ochraceous ; in the 9 the whole ab- 

 domen is brown, the genitals being pale ferruginous. The wings ure of a satu- 

 rated fulvous tinge, with a peculiar bluish, opalizing reflation ; the veins are 

 fulvous and distinctly pubescent ; if looked at obliquely, the veins appear yellow 

 on a bluish ground. The neuration is described among the characters of the genus. 

 No distinct stigma. The stigraatical cross-vein is very near the tip of the sub- 

 costal vein ; the mediastinal vein reaches a little beyond the origin of the cubital 

 area; the latter is longer than the subapical area by about half the length of 

 the discal areolet ; the great cross- vein is a little before the middle of the latter ; 

 the upper discal cross-vein is generally straight, but in a couple of specimens 

 it is oblique and arcuated. In one specimen the petiole has a short stump of a 

 vein near its origin. 



Eight male and nine female specimens, caught near Trenton Falls, where 

 this species was very common in July, 1858. 



N. B. The description is drawn from dry specimens. Among the notes 

 which I took on living ones, I find the following character mentioned: "ab- 

 domen yellow, with five brown spots along the lateral margins at the incisures." 



D. s o b r i n a. Cinerea, alis subcinereis ; long. lin. 4 4J. 



Head subcinereous ; proboscis tawny ; palpi and antennae black (in some 

 specimens the antennae are paler at the base) ; verticils of the latter long. 

 Thorax cinereous ; praescutum with three indistinct, infuscated stripes ; pleurae 

 hoary ; halteres pale ; knob slightly infuscated ; feet tawny, densely clothed 

 with a moderately long black pubescence ; coxae pale ; tips of the femora a 

 little darker ; those of tarsi brown. Abdomen cinereous ; venter paler; genitals 

 pale ferruginous; tf forceps like fig. 13. (See its description appended to the 

 plate.) Wings subcinereous, iridescent, neuration similar to that of the pre- 

 ceding species ; veins clothed with moderately long hairs ; the anterior margin 

 of the wing with a fringe of dense, short hairs. 



Seven male and five female specimens ; caught near Washington, D. C, in 

 June, 1859. 



D. nigripes. Fusco-flava, pleuris cano-micantibus ; pedibus dense 

 nigro-pubescentibus ; femoribus anticis annulo flavo ; ventre nigro-maculato ; 

 length 4 lines. 



Head cinereous ; antennae black ; two basal joints ferruginous-yellow ; pro- 

 boscis brownish, palpi black. Thorax brownish yellow ; pleural, scutum, scu- 

 tellum and metathorax with a hoary reflection ; the latter blackish at the basis ; 

 halteres pale; coxae and base of femora yellowish-ferrugineous, the rest of the 

 feet clothed with a dense black pubescence, which almost entirely conceals the 

 tawny color of the ground ; tip of femora black, with a yellow ring before it, 

 which is especially distinct on the anterior pair. Abdomen brownish yellow ; 

 the segments of the venter, from the third to the seventh, have transverse black 

 spots in the middle ; <$ forceps represented in figure 12a, and described in the 

 explanation of the plates. Wings tinged with brownish yellow, which color 

 appears more saturated and almost, ferruginous along the costal margin ; there 

 is a fringe of black hairs along the apical margin, between the tip of the sub- 

 costal vein and the externo-medial veins ; the surface of the wing itself is slightly 

 infuscated along this fringe. Neuration almost like the preceding species ; veins 

 finely pubescent. 



One J 1 specimen from Dalton, Ga. (nob.) ; the description was drawn from 

 it when it was yet fresh. v 



D. sororcula. Thorace pallide cervino, vittis obsoletis ; pedibus pallidis ; 

 alis pallide fusco-cinerascentibus ; length o\ 4 lines. 



Head pale brownish yellow with a light grey tinge ; palpi brown ; antenna? 



[Aug. 



