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The Ohio Naturalist. 
[Vol. V, No. 2, 
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Antenn;e black, or at most with a trace of red at the base of the 
third segment .31 
Antennae largely red 33 
Subcallus denuded centron 
Subcallus not denuded 32 
Wing with brown blonds on the cross- veins and the furcation of 
the third vein sonomensis 
Wing with no clouds on the cross-veins and furcation of the 
third vein phmiops 
Front of the female unusually wide above, distinctly narrowed 
anteriorly captonis 
Front of the female not unusually wide, sides nearly parallel 34 
Third antennal 'segment fully as broad as long laticornis 
Third antennal segment longer than wide 35 
Costal cell brown 36 
Costal cell hyaline 37 
Palpi robust epistatus 
Palpi slender ajfinis 
Head decidedly wider than the thorax laticeps 
Head not noticeably widened 38 
Base of the anterior branch of the third vein with a stump frenchii 
Base of the anterior branch of the third vein not with a 
stump SHSurrus 
Tabanus aegrotus Osten Sacken. Easily identified by Osten 
Sacken’s description. It appears some like our eastern atratus, 
but the wings may be said to be subhyaline instead of black as in 
that species. Usually the whole body is black, but in some spec- 
imens the abdomen above has a median row of very small white 
triangles, one on the posterior border of each segment. 
Tabanus affinis Kirby. There is some variation in the e.xtent 
of red on the abdomen. This seems to occur in specimens from 
the same locality to the same extent as in specimens from differ- 
ent localities. Its size, fifteen to nineteen millimeters, makes its 
determination rather easy, as it is the largest of our species with 
pilose eyes. Some specimens of athnis and some of sonomensis 
are rather close together, but the third segment of the antennae is 
narrower in sonomensis and the basal process less prominent. 
The palpi are very slender in afiinis. 
Tabanus annulatus Say. Rarely collected and probalby there 
is not more than a dozen good specimens in the collections of the 
country. The front is narrow and the frontal callosity and what 
in other species is called the spindle shaped line, unite to form a 
very narrow raised line of nearly uniform width reaching nearly 
to the vertex, eyes naked, a small ocelligerous tubercle. Thorax 
uniform gray, abdomen brown with a gray posterior border to 
each segment; wings hyaline. Length 12 to 14 millimeters. 
Taken as far west as Kansas and Missouri. The species is one 
of the anomalies of its family. 
Tabanus atratus Fabricius. Its large size and black color 
serve to separate this species from all others of the western 
region. Taken as far west as Colorado. 
