SYNOPSIS OF NORTH AMERICAN SYRPHID^. 47 



Melanostoma (?) rufipes. 



Chciloi<iu rufijyes Williston, Proc. Am. Phil. Soc, xs, 306, 1882. 



Habitat. — Washington Territory ! 



9 . Lengtli, 8 to 9 """. Face shining black, except the prominent tuber- 

 cle and the cheeks, partially concealed beneath even, whitish pollen. 

 Front a little narrowed above ; below the middle a shallow, transverse 

 depression, on each side of which there is a triangular whitish pollinose 

 spot near the eye, continuous along the eye narrowly to the face. An- 

 tennse blackish, third joint a little elongate, reddish on the under side. 

 Thorax metallic green-black, finely puuctulate, nearly bare, the pubes- 

 cence whitish. Abdomen elongate oval, the third segment of nearly 

 equal width throughout, not narrowed behind: first segment shining; 

 second segment on the sides with a large triangular spot, extending the 

 whole length of the segment on the sides, light green, moderately shin- 

 ing, elsewhere sub-opaque black, with a slight greenish reflection; 

 third segment similar, but the spots more narrowly separated ; on the 

 fourth segment the spots are confluent, forming an entire cross-band, 

 concave behind, the remainder of the segment shining bhick ; remain- 

 ing segments wholly shining greenish. Legs dark red, rather stout; 

 the hind femora, or all the femora, more or less brown or blackish at 

 the base ; hind metatarsi a little thickened. Wings short, projecting 

 but little beyond tip of abdomen, nearly hyaline ; stigma dilutely yel- 

 lowish. 



Four specimens, Washington Territory. 



Until the male of this species is known, its position is somewhat 

 doubtful. Its relationship to Chilosia is very strong, but the distinctly- 

 banded abdomen would seem to remove it from that genus; possibly it 

 is a Platychirus. With these four specimens is a fifth, agreeing through- 

 out in every respect with the others, except that the femora are a little 

 darker, and the abdomen, except the first segment, is of a uniform 

 deep red. The color seems not to be due to immaturity. 



Melanostoma tigrinum. (Plate III, lig. 8.) 



Melanostoma tigrina Osten Sackeu, West. Dipt., 323. 



Hahitat.—W ashmgton Territory, California, Colorado, Arizona ! 



^ . Length, 6 to 9 '"'". Face and front dark metallic grfeen, the former 

 with white pollen, forming transverse, irregular dotted ripples, the in- 

 tervals of which show the ground color ; the cheeks and a stripe running 

 over the facial tubercle are bare of pollen ; facial tubercle obtusely 

 projecting. Antennse black, third joint and arista brown, or reddish. 

 Front faintly and evenly grayish pollinose and with erect black pile; 

 vertical triangle metallic green, with black pile. Thorax metallic bluish 

 green, clothed with dull grayish pile, more whitish on the pleural. Hal- 

 teres brownish. Abdomen elongate-elliptical, broadest at the hind mar- 

 gin of the second segment ; first segment greenish black ; the second 

 velvet-black opaque, the lateral edges metallic olive green with a small 



