arr. 4. REVISION OF THE FAMILY THEREVIDAE—COLE. ELS 
tinged brownish; cross veins and fork brownish bordered. Stigma rather dark 
brown. Femora blackish brown; the four first ones long erect pilose, blackish 
brown or light according to the illumination. Hind femora sparsely short reclinate 
pilose. Tibiae and tarsi yellowish brown, the tips darkened. Length 13 mm. 
Type locality.—Southern Colorado. 
Type.—In the Hofmuseum, Vienna. 
The National Museum contains a male specimen, determined by 
Kroéber, from Wisconsin. 
THEREVA FRONTALIS Say. 
Plate 10, fig. 121, and plate 11, fig. 150. 
1824. Thereva frontalis Say, Long’s Exped. to St. Peters River, vol. 2, p. 370. 
Type locality.—‘“‘ N. W. Territory.”’ 
Type.—Not in existence. 
The species is redescribed below: 
Male.—Length 10 to 11 mm. Head black, gray pollinose, the 
upper corner of frontal triangle black; frons black pilose. Face and 
occiput white pollinose, the outer margin of face and a spot beneath 
the eye black pilose, the rest of face and occiput white pilose. Palpi 
brown, white pilose. SBristles of occiput black. The antennae black, 
first joint about the length of third ,gray pollinose, with black pile 
and bristles. 
Thorax black, gray pollinose; mesonotum with a median blackish 
brown stripe and two indefinite whitish vittae, on the outer side of 
which is some brown pollen. Scutellum gray pollinose with very 
fine blackish pile and four black bristles. Pile of mesonotum erect 
and blackish. Pleura gray pollinose, white pilose, with a few black 
hairs in the cluster of pile before the base of wing. Stem of halteres 
yellowish, the knob black, largely gray pollinose. 
Abdomen black, largely gray pollinose, the hind margins of second, 
third, and fourth segments narrowly whitish; base of first to sixth 
segments with a large, semicircular blackish brown spot, rounded 
posteriorly and almost reaching the posterior margin. Genitalia 
blackish on the exterior, the hypandrium with very short projections 
(fig. 150) and yellow pilose, the upper portion with black pile on the 
outside. Sixth and seventh segments black pilose; the first to fifth 
black pilose on the dorsum, white on the sides, long, erect, and 
rather sparse. Venter gray pollinose, the posterior borders of seg- 
ments two to five yellowish white; pile of the first four segments 
white, beyond this black. Femora black, the short reclinate pile of 
the hind pair black, a few erect white hairs at the base; pile on the 
four front femora largely long, erect, black, a few white hairs above; 
knees yellow; tibiae yellow with black tips; most of the tarsi black, 
the first joint and sometimes the base of the second yellowish. 
