40 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



bronze black, with greenish reflections, overlaid with gray dust. Abdomen 

 dull metallic green, bases of segments and small, almost completely 

 imbedded hypopygium, black. Hairs and bristles covering the abdomen 

 black, long towards the posterior edges of the segments, especially on the 

 edge of the first segment; first and second segments with long and pro- 

 jecting, but rather delicate white hairs along their sides. Sides of the seg- 

 ments thinly, venter more thickly covered with gray dust. Pleurae and coxae 

 dull metallic green, overlaid with white dust, the latter with yellow tips and 

 white hairs; each coxa also bears a prominent black bristle, the fore and 

 middle coxa on the anterior surface near the tip, the hind pair on the poste- 

 rior surface near the middle. Legs yellow; fore femora metallic green 

 except the apical third; middle femora metallic green only at the base; hind 

 femora with two broad metallic green bands, one at the base and one near 

 the apex. Fore tibiae with a row of regular short black bristles on the ante- 

 rior surface; middle femora ciliated with black bristles on their lower sur- 

 faces; hind tibiae somewhat incrassated towards their tips but not black- 

 ened; both the middle and hind tibiae rather bristly; fore and middle tarsi 

 blackened from the tip of the first joint. Hind tarsi entirely black ; hind 

 metatarsus somewhat thickened and distinctly excavated on its plantar sur- 

 face where it bears near the proximal end two strong and somewhat recurved 

 black bristles. Second joint of hind tarsi equalling the first in length. Wings 

 grayish hyaline, not narrowed towards the base, so that the anal angle is 

 prominent; third and fourth veins divaricating very slightly towards their 

 tips in the costa; third vein near its termination distinctly but gently bent 

 down towards the fourth. Posterior cross-vein of about the same length as 

 the distal segment of the fifth vein. Halteres and tegulae yellow; the latter 

 margined with black and bearing delicate white cilia. 



Female. Length 5 mm. ; length of wing 4 mm. Face and palpi covered 

 with plumbeous dust, the former very broad and produced below into a pro- 

 jecting roof-shaped epistoma, overhanging the palpi and proboscis. Antennae 

 small; third joint about as long as broad, with a very short, blunt apex, on 

 which the arista is inserted; pile short; arista of about the same length as in 

 the male, with scarcely perceptible pubescence. Overlapping lobe of second 

 joint well developed; first joint short, with a distinct ventral projection 

 smaller than that of the male. Coloring of the thorax, scutellum and abdo- 

 men like the corresponding parts of the male, but the white hairs on the 

 basal segments of the abdomen are less prominent. Legs plain; middle and 

 hind femora entirely yellow; basal half of fore femora infuscated. Wings 

 more yellowish brown than in the male, especially along the posterior cross- 

 vein and near the middle of the distal segment of the fourth vein. 



Four males from Lusk, Wyo., collected by Mr. W. A. 

 Snow during July, 1895, and a male and female collected 

 by myself near Monterey, Calif., during July, 1896. 



This is the largest of the North American species known 

 to me. The males are readily recognized by the peculiar 

 structure of the hind metatarsi. 



