art. 4. REVISION OF THE FAMILY THEREVIDAE—COLE. 23 
nose. Base of scutellum narrowly shining black, most of disk sil- 
very white pollinose, the margin dull black with two bristles. Pleura 
and coxae silvery gray pollinose. Knobs of halteres white, the stems 
pale brownish. 
Abdomen shining black, first segment gray pollinose, the rest shin- 
ing; the short pile reclinate and whitish; pile on the last two segments 
black. Genitalia the same as in the other two species of the genus. 
Second and third abdominal segments with narrow posterior margins 
of white. Coxae partly yellowish, femora yellowish, the two front 
pair brown above; tibiae reddish yellow, white pilose, the tarsi black- 
ish; front tibiae largely whitish yellow, with dense silvery white pile 
in front. Wing venation the same as in the other two species; vein 
M-2 reaches the margin of the wing in the single specimen. 
Type locality—Holotype, female, collected at Highley, Arizona, 
June 13, 1917, on Superstition Mountain (I. G. Holt). 
Type.—tIn the collection of the United States Biological Survey. 
The unique type is closely related to the other two species of the 
genus, but is distinguished by the marking of the thorax, the yellow 
femora, etc. 
CHROMOLEPIDA, new genus. 
Small species, very near Psilocephala in general appearance. An- 
tennae long and slender, the first joint longer than the second and 
third, and with no distinct bristles, but short hairs. ‘The orbital 
bristles are very short and set back from the vertex so that only a 
few show from the front. Eyes holoptic in the male and widely 
separated in the female. On the upper face just below the antennae 
are two shining black callosities. Cheeks projecting below the eyes 
more than is usual in Psilocephala; the palpi and proboscis are much 
the same. Mesonotum, pleura, and coxae more or less clothed with 
scales, many of which are iridescent; in perfect specimens there is a 
dense covering. This vestiture is not found in any other genus in 
the family. Abdomen of the male as in Psilocephala, but with scales 
on the dorsum, venter, and sides in addition to the pile; in the female 
there are very few scaies. The male genitalia are of the general type 
found in Thereva and Psilocephala, as are the female genitalia. The 
wings are rather short, unusually short in proportion to the body in 
the female. 
Genotype.—P silocephala pruinosa Coquillett. 
TABLE Of SPECIES. 
First two antennal joints yellow; frons without a velvet black spot. 
pruinosa (Coquillett). 
First two antennal joints black; frons with a velvet black spot near the middle, 
bella, new species. 
