Jan., 1914.] Tabanus Longus, Fulvulus and Sagax. 
225 
TABANUS LONGUS, FULVULUS AND SAGAX. 
Jas. S. Hine. 
These three species of North American horseflies have proven 
more or less troublesome from the standpoint of determination on 
account of their resemblance to one another and the variation 
among different specimens of each species as well as their general 
aspect which corresponds very closely with several other species 
of their genus. 
The following combination of general characters will serve well 
to group the three species in question and separate them from 
others similar in appearance: the wings are transparent with no 
vestiage of infuscation on the cross veins or furcation of the third 
vein; no suggestion of a stump of a vein on the anterior branch 
of the third vein in any of the specimens I have examined; the 
costal cell is transparent or very pale yellowish; the general color 
of all specimens is yellowish or brown, never black; the abdomen 
has a middorsal stripe with a row of spots on each side; these 
spots are usually rounded and do not reach the hind margins of 
their respective segments; in longus the dorsal stripe is narrow 
and nearly always abbreviated posteriorly and in rubbed speci¬ 
mens may disappear altogether. The characteristic thing about 
the middorsal stripe in the three species under consideration is 
its widening on the posterior margin of each segment thus pro¬ 
ducing an irregular stripe quite different from the regular stripe 
in costalis, linecla and a long list of other North American species. 
With the material at hand the opportunity is given for a 
study of variation. Each of the three species has been divided 
into series mainly from the standpoint of coloration and size as 
not much variation in structure is apparent. Colorati n appears 
to be largely a matter of locality and almost invariably specimens 
from southern regions are decidedly smaller than those taken 
well north. 
The following key should be of use in separating the species 
here considered: 
1. Third segment of the antenna narrow, without a distinct angle near 
its base on the dorsal side, sagax. 
Third segment of the antenna wider, with a distinct angle near its base 
on the dorsal side. 2. 
2. Thorax yellowish, without stripes, middorsal abdominal stripe 
distinct, front in the female narrow, fulvulus. 
Thorax brown, often faintly striped, middorsal abdominal stripe narrow 
and usually more or less abbreviated posteriorly, front in the female dis¬ 
tinctly wider, longus. 
