3°8 
The Ohio Naturalist. 
[Vol. XI, No. 6, 
directed outward in some specimens. Hypopygium rather large 
with an extension at the apex and clothed with rather long yellow 
hairs among which are some black ones. 
Female abdomen nearly uniform yellowish pollinose with pale 
hairs, ovipositor about five millimeters in length, equivalent to the 
last three abdominal segments. Several specimens from Colorado 
and New Mexico. 
Erax dubius Williston. Gray all over, femora black, tibiae and 
tarsi red, the latter somewhat darker than the former, tibiae with 
apices somewhat darkened. Total length of the male. 21 mil- 
limeters. 
Mystax and beard white, ocellar bristles rather large and 
black, occipito-orbital bristles mostly black, otherwise the hairs 
and bristles of the rear of the head are white, palpi black and 
clothed with white hairs; legs with black bristles and white hairs, 
on the tibiae this white hair is long and conspicuous, but on the 
femora it is in large part short and recumbent ; wings hyaline, very 
slightly darkened at extreme apex; thorax gray pollinose, most of 
the hairs and bristles of the dorsum black, of the sides white, 
scutellum with white hair, and black bristles on the margin. 
First four abdominal segments with long white hairs which on 
two, three and four are parted at the middle and directed outward, 
fifth and following segments white and with very short white 
hairs. Flypopygium from above narrower than the last abdominal 
segment, black, with hairs mostly white, apex truncate except that 
the upper part of each valve is extended backward and inward 
toward its fellow of the opposite side thus producing a prominence 
from lateral view. 
I take this to be the species to which Williston gave the name 
dubius in the Transactions of the American Entomological Society 
XII, page 64. No description of the species appears to have been 
written but the name is inserted in the key and enough characters 
pointed out to make identification reasonably certain. There are 
two males before me from southern Arizona. 
Erax argentifrons n. sp. Much like rapax. Front white pol- 
linose, mystax white, legs with white hair. Length 18 to 23 
millimeters. 
Palpi black with white hair, occipito-orbital and ocellar 
bristles black, antennae black, first two segments with white hair, 
beard white. Thorax yellowish-brown with the usual middorsal 
stripe darker, hairs of the sides almost uniformly pale, of dorsum 
variable between pale yellowish and black; wings hyaline, legs 
black, except the extreme bases of the tibiae which are reddish- 
yellow, clothed with white hairs and black bristles. 
First two segments of the male abdomen colored like the 
thorax, segments three to seven inclusive silver white, apex of 
tw r o, all of three and four with long white hair parted at the mid- 
