HORSEFLIES OF THE SUBFAMILY TABANINAE Dil 
black; basal callus slightly wider than high, irregular, narrowly separated from 
subcallus and rather broadly so from eyes; median callus irregular, subquad- 
rate, nearly as wide as basal callus; subzallus slightly protuberant, the ground 
eolor yellowish, with thin concolorous pollen. Antenna yellowish orange, the 
annulate portion slightly darker; first two segments with black hair; basal 
portion of third not excised dorsally; a few black hairs just basad of the 
obtuse dorsal angle; annulate portion stout, slightly shorter than basal por- 
tion. Clypeus and genae concolorous with frons, with mostly concolorous hair. 
Palpus pale yellowish, with mixed black and pale-yellowish hair; second seg- 
ment stout basally, tapering to acute apex; proboscis not much longer than 
alpus. 
3 Ree wo taint including prescutal lobe, black, with erect black and recumbent 
yellowish hair. Pleura, sternum, and coxae grayish tinged with yellow, the 
hair pale yellowish. Wing hyaline, the veins yellowish brown basally, dark 
brown apically; vein R.z angulate basally, the stump vein scarcely evident. 
Femora dark grayish brown; tibiae and tarsi yellowish brown, the fore tibia 
apically and fore tarsus dark brownish black. 
Abdomen dark grayish brown, faintly yellowish on sides of second tergite; 
median and sublateral spots of paler hair scarcely visible. 
Male.—Eye densely pilose, the areas of large and small facets rather well 
differentiated along the narrow, diagonal, purple band; pollen and hair of 
head gray, scarcely tinged with yellow; second palpal segment stout, the apex 
acute and slightly turned downward. Body coloration essentially as in female. 
Vein R: with a moderate stump. 
Type.—One of nine cotype females in the Museum of Comparative 
Zoology (No. 14518) labeled and herein designated as lectotype. One 
cotype in the collection of C. B. Philip. 
Type locality.—Webber Lake, Calif. 
Distribution—Southern Alaska and Saskatchewan to central Cali- 
fornia and Colorado. May 18 (Dolomite, Utah) to September 10 
(Topaz, Calif.). In the United States National Museum, 54 females, 
10 males. 
The foregoing descriptions are based upon the lectotype and a 
male in the collection of C. B. Philip very closely resembling the 
lectotype. These descriptions will not fit accurately the many tinc- 
torial and structural variations occurring in this species or species 
complex. Osten Sacken noted certain variations in the type series; 
Hine referred to the extremely variable nature of the species; Philip 
also discussed this variability and named a variety; utahensis Rowe 
and Knowlton is, the writer feels, at most a variety. The coloration 
of “?nsuetus” varies all the way from the pale, dusty yellowish of 
utahensis to specimens even darker than the type; the pleural hair 
may be strongly orange brown as in the variety tingaureus, yellow 
as In certain specimens from Topaz, Calif., or nearly white as in 
some specimens from Colorado; the abdomen may be entirely uni- 
colorous, distinctly paler laterally, or may have three rows of dis- 
tinct, pale spots; the prescutal lobe ranges from black to pale yellow; 
the femora show the same variation; the third antennal segment may 
be entirely yellow, yellow with the annulate portion black, or entirely 
dark brownish. Structurally the frons may be as broad as in the 
type or considerably narrower; the stump vein from R, may be 
absent or iong; the frontal calli vary considerably in size and may 
or may not be connected. 
With all of the variation mentioned, it would seem possible to select 
one or more characters to delimit varieties or even species. With 
some 150 specimens at hand, however, the writer has been unable to 
do so, there being intergradation or overlapping of both structural 
and tinctorial characters throughout. It is possible that suitable 
