42 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 68 



shorter than head height; palpi well developed. Thorax with two 

 sternopleural bristles. Genitalia of male (pi. 1, fig. 5), small, and 

 in repose, scarcely protruding from tip of abdomen; of female, re- 

 tracted and non-piercing. Wings with apical cell open; last section 

 of fifth vein distinctly less than half as long as preceding section; 

 costal spine wanting; middle tibia with one macrochaeta on outer 

 front side near the middle; hind tibia on outside with row of uneven 

 bristles extending from base to apex. 



KEY TO NORTH AMERICAN SPECIES OF OPSIDIA 



1. Front, at base of antennae, twice as wide as either eye; arista thickened 



nearly to tip gonioides Coquillett. 



Front, at base of antennae, as wide as either eye; arista thickened on less than 

 the basal half metopioides, new species. 



OPSIDIA GONIOIDES Coquillett 



Opsidia gonioides Coquillett, Journ. New York Ent. Soc, vol. 3, p. 102* 

 1895; U. S. Bur. Ent., Tech. Ser., no. 7, p. 128, 1897.— Smith, Ins. of 

 New Jersey, p. 782, 1909. 



The distinctive characters of this species are as follows: Female 

 closely resembles the male. Inner orbits parallel from vertex to 

 bucca; front approximately twice the width of either eye and of equal 

 width in both sexes; ratio of front to head width in males averages 

 0.496 (in five measuring 0.49, 0.49, 0.50, 0.50, 0.50), in females 

 averages 0.493 (in four measuring 0.48, 0.48, 0.50 and 0.51) ; the frontal 

 vitta is red, densely overlaid with golden pollen; much narrower at 

 base of antennae, expanding abruptly at middle to width greater 

 than either parafrontal; ocellar bristles directed laterally; one reclinate 

 and two proclinate orbital bristles present, parafrontals densely black 

 setulose, the bristly hairs continuous downward over the parafacials, 

 to tip of antennae; vibrissae inserted more than length of second 

 anteunal joint above front edge of oral margin, but a collapsible 

 membranous area at this point makes this character widely variable; 

 second joint of antennae red; third joint black; arista thickened on 

 basal four-fifths; parafacials \vith a row of small macrochaetae 

 bordering facial ridges; palpi yellow; in profile, buccal width is sub- 

 equal to that of parafacials and equal to one-fifth eye height, front 

 projects a distance nearly equal to horizontal eye diameter. Thorax 

 densely poUinose, with two somewhat obscure, divergent median 

 vittae, and a pair of lateral convergent vittae most clearly defined 

 caudad of transverse suture; three postsutural dorsocentral macro- 

 chaetae, of which the first is scarcely chfferentiated from the sur- 

 rounding bristly hairs; scutellum with three pairs of strong, nearly 

 equal macrochaetae. Abdomen densely gray pollinose, with dark 

 reflections, but without definite spots or polished apical bands; 

 second segment, and usually the first, with a median marginal pair 



