30 PROCEEDINGS OF THE NATIONAL MUSEUM vol. C6 



parallel with third at tip ; last section of fifth vein one and a half 

 times as long as the crossvein. 



Female. — Differs from the male only in having the face wide; 

 third antennal joint small, about as long as wide and the cilia of the 

 calypters are yellow, not black as in the male. 



Described from three males and four females (including type 

 and allotype) taken by Dr. J. M. Aldrich at Lawrence, Kansas; 

 eight males and three females taken by C. F. Adams at Atherton, 

 Missouri, in May and June; and one male and two females taken 

 by G. R. Pilate at Opelousas, Louisiana, in May. 



This species is remarkable for its yellow antennae, the third joint 

 of which has a black line above, and the yellow lamellae with black 

 dots on their surface where hairs are inserted. 



Tyfe^ allotype., and 6 faratyjjes. — Male and female. Cat. No. 27050, 

 U.S.N.M., from Kansas and Louisiana. 



31. ARGYRA OBSCURA, new species 



Male. — Length, 4.7 mm. Face rather wide, with silvery white 

 pollen ; still it appears black and a little shining when seen from in 

 front. Palpi and proboscis black with black hair. Front greenish 

 black with white pollen, which is thick near the antennae. Antennae 

 black, jfirst joint with conspicuous hairs above; third joint about as 

 long as the basal two taken together, arista apical, equal to the 

 antenna in length. The small black orbital cilia reaching down 

 nearly to the middle of the eye ; below these there is a quite abundant 

 white "beard. 



Dorsum of thorax and the scutellum blue-green, the former with 

 considerable white j^ollen, which is thick on the humeri and along 

 the sides to the root of the wings ; humeri with several small bristles ; 

 there are four black bristles above the fore coxae; scutellum with 

 four marginal bristles, and many black hairs on its disk. Abdomen 

 dark green, all its hairs and bristles black; it has rather dense 

 white pollen on the base of the segments; second segment with a 

 rather large but obscure yellow spot at base on each side; there is 

 also a small indistinct yellowish spot on each side of third segment 

 at base. Hypopygium black, its tip and the large sheath or inner 

 appendage testaceous; outer lamellae black with pale hairs and black 

 bristles. 



Coxae wholly black; trochanters yellowish; fore and middle coxae 

 with long, bristly, black hairs; hind coxae with two bristles and 

 several hairs on outer surface. Fore and middle femora black with 

 narrow yellow tips; hind femora with basal two-thirds yellow, 

 apical third black; fore femora with black hair on posterior surface, 

 which is scarcely as long as their thickness; middle femora with a 



