1923 ] 
The Genus Cyrtopogon 
117 
Male . — Length 10 mm. Antennae black, third joint broad- 
ening underneath, thickest at two-thirds its length, style one- 
fourth as long as the third joint; front and face heavily silvery- 
gray, occiput subshining, more whitish at orbits, facial gib- 
bosity nearly hemispherical, its central hairs long and silvery- 
white, mystax entirely black, beard largely white, frontal hairs 
long, delicate, not abundant, black. Thorax viewed from 
above presenting the following pattern in dark brown pollen: 
a bisected median stripe contiguous with a presutural round 
spot, and the entire postsutural area except postalar callosities 
and a narrow triangle in front of the convex shining scutellum, 
— this brown picture changing to shining black when viewed 
from behind; viewed from in front the anterior portion of the 
mesonotum is silvery-white pruinose, but from above a 
posthumeral area appears subshining black; all hairs of 
thorax black; pleurse subshining lightly coated with brownish 
dust, but whitish pruinose above front coxae, on upper 
sterno pleura and narrowly along posterior part of mesopleura. 
Abdomen polished black with slight violaceous tinge, lightly 
dusted on apical segments, hypopygium polished, interrupted 
silvery-white fasciae along posterior part of segments 2-6, 
narrowly leaving the hind margin on segments 2, 3 but at- 
taining the hind edge on segments 4-6, the marks of the sixth 
segment less distinct, all hairs of abdomen black, those at sides 
of first three segments long and almost tufted. The silvery 
hairs of front tarsi cover the ground-color; the middle tarsi are 
always black, the front and hind ones sometimes are brown but 
usually are quite black; inner face of front tibiae and metatarsi 
densely coated with glistening fulvous depressed short pubescence, 
similar fulvous pubescence extends along posterior face of hind 
tibiae; pul villi and basal third of claws brown. Halteres with 
yellowish knob; wings with brownish tinge and with brownish 
markings occupying the root, auxiliary cell, furcation of veins, 
crossveins, and forming an oblique band along first section of 
third vein, the anterior crossvein at basal fifth of discal cell. 
Female . — Larger by one or two millimeters. Front largly 
lightly dusted with brown, face and central hairs less pure white. 
