ALDRICH AND DARLINGTON. 79 



4. Two or more sternopleural bristles •'>• 



Only one sternopleural bristle 6. 



5. Color pale yellow biseta Loew. 



Color black or brown iners Meigen. 



6. Pteropleura with one bristle and several hairs (halfway between the sterno- 



pleural bristle and the root of tlie wing) pectiiiata Loew. 



Pteropleura bare '■ 



7. Thoracic dorsum yellow in ground color 8. 



Thoracic dorsum black in ground color, or mainly so 10. 



S. Large species (10 mm.), yellow, the abdominal segments sharply banded with 

 black behind hel vola Loew. 



Small species (4 to 5 mm.), abdomen not so marked 9. 



f). Scntellum flat Intea Loew. 



Scutellum convex discolor Loew. 



10. Abdomen wholly dark yellow, contrasting with the thorax. 



serrata Linn. 

 Abdomen not wholly yellow 11- 



11. Femora and tibife wholly yellow 1~- 



Femora and tibite partly blackish 13. 



12. With one vibrissa Jristis Loew. 



With two vibrissie. the hind metatarsus of the male shortened. 



latent Aldrich. 



13. Hind femora of the male with a comb of nine truncate black bristles below 



near the middle cineraria Loew. 



Hind femora not so marked 14. 



14. Humeri yellow 15. 



Humeri not yellow crassipes Loew. 



1.^. Arista short, not over twice as long as the body of the antenna. 



leucostonia Loew. 

 Arista considerably longer glauca n. sp. 



Leria fraterna Loew. 



Scoliocentra fraterna Loew, Centuries, iii, 51. 

 Lena fraterna Coquillett, Wash. Acad. Sci., ii, 457. 



Chocolate-brown, with a slight glaucous coating and a dense covering of fine 

 black hair on body and legs. 



Head yellow, occiput and ocellar triangle brown, with a whitish pruino.sity; 

 front with numerous fine black hairs, extending down on the sides below the 

 base of the antennas ; anterior fronto-orbital more than half as long as the poste- 

 rior; cheeks fully half the height of the eyes, hairy on the lower half; palpi 

 yellow; one vibrissa; antenna? leddish-brown, short, the arista of moderate 

 length, thin, black. 



Thorax chocolate-brown, with a whitish pruinosity, everywhere covered with 

 soft, woolly black hair, except on the scutellum, metanotum, metasternum and 

 posterior half of the pteropleura; all the bristles except the scutellar are more 

 slender than usual, the anterior three dorso-centrals and the humeral almost 

 imperceptible; the position of the dorso-central row on each side is marked by a 

 faitit, interrupted brown line; scutellum bare, yellowish-brown; halteres yel- 

 low; one sternopleural bristle. 



TRANS. AM. KNT. SOC. XXXIV. MARCH. 1908. 



