ART. 4. REVISION OF THE FAMILY THEREVIDAE—COLKE. 39 
very white pollinose, a few short black hairs on each side of the me- 
dian black frontal stripe. Antennae black, rather slender, the third 
joint a little longer than first and slightly wider in the middle; first 
and second joint and base of third with black bristles. Palpi brown 
with long white pile; post-ocular bristles black; cheeks with a black 
spot below the eye on which there is short black pile; cheeks and 
occiput white pilose; occiput gray pollinose above and white below. 
Thorax black, more or less shining on sides of mesonotum, the dor- 
sum bluish gray pollinose; a median black stripe, narrowed at the 
anterior and posterior ends; on each side of the median stripe a nar- 
row, faint whitish stripe. Pile on the margins of the mesonotum 
white, brownish black on the central part of the dorsum. Scutellum 
gray pollinose, white on the posterior margin, with four black bristles 
and short white pile. Pleura except a large part of pteropleura dense 
silvery white pollinose, the pile white; very long pile before the hal- 
teres. Knob of the halteres blackish, the stem yellowish. 
Abdomen black, largely gray or silvery gray pollinose, most of the 
dorsum bare of pile; the second to sixth segments silvery tomentose, 
bright in certain lights; a shining black spot on the sides of the second, 
third, and fourth segments near the base. Pile of the abdomen white, 
longer at the base, reclinate on the dorsum. The seventh segment 
scarcely visible in most specimens; genitalia reddish and yellow, with 
a few short yellow hairs, but mostly scattered Jong black pile. Femora 
black, appressed silvery white pilose, with some longer erect white 
pile below and behind on the two front pair; base of front tibiae and 
first tarsal joint yellowish, the rest black; on two hind pair of legs 
the tibiae and first two tarsal joints yellow except the blackish tips 
the other tarsal joints black; bristles of legs black. Wings hyaline, 
the stigma brown, the veins yellow at the base and in the costal 
region, otherwise brown; a pale brown spot at the outer side of the 
cell first M-2; cell M-3 closed and short petiolate. 
Female.—Length about 7 mm. Closely resembling the male; bris- 
tles of first antennal joint shorter; frons shining black, slightly convex, 
smooth, the lower corners silvery pollinose (fig. 47), the vertex and 
ocellar tubercle gray pollinose. 
Pile of mesonotum very short, black along the median line, on each 
side appressed yellowish; the lateral margins of the mesonotum short 
white pilose. Center of scutellum and the base black, the margin 
whitish pollinose; four black marginal bristles as in the male. Pile 
of pleura and coxae much shorter than in the male. 
First segment of abdomen gray pollinose and white pilose, the rest 
of the abdomen shining black except the narrow posterior silvery 
margins of the second and third segments, the dorsum and sides of 
the fifth, and a silvery spot on the sides of the sixth. The pile of the 
first three segments short, reclinate, and white, on the other segments 
