19463 Tabanidae of Colombia 87 
basal callus shiny, dirty-yellowish, touching the inner orbits, 
nearly twice as wide as high, rather abruptly extended upward 
into a median broad line, which is triangularly widened at the 
base and reaches to about mid-length of frons; middle third of 
frons with a large, dull, cordiform spot of velvety-black pol- 
linosity, the broader lower end notched and divided by the 
smooth extension of the basal callus, the narrowed upper end 
jagged; remainder of frons and vertex gray pollinose, the vel- 
vety spot broadly separated from inner orbits; vertex flat, with 
a small brownish-pollinose median area; frons with many erect, 
black hairs, even on the shiny callus. Proboscis short, thick, 
with large, soft labella. (Antennae and palpi broken off.) Eyes 
densely covered with erect grayish hairs. Thorax black, mostly 
covered with ashy-gray pollinosity, except dorsally over four 
broad, blackish, longitudinal stripes; of the five grayish-white 
stripes thus produced, one on each side is very broad and divided 
posteriorly (above the wing base) by a short blackish streak; 
three in the middle are much narrower; the median one linear, 
slightly widened behind where it stops at the posterior third; 
the two admedian ones reaching the scutellum where they unite 
with the lateral stripe on each side, but broadly interrupted 
beyond mid-length of the dorsum; scutellum mostly with black- 
ish pollinosity, the hind margin broadly gray pollinose. Hairs 
of thorax long, dense and white beneath, dorsally long, sparse, 
mostly black with a mixture of white particularly near the sides 
and at the hind margin of the scutellum. Abdomen: integument 
black, with indefinite slightly brownish areas at the sides of the 
first tergite; ventrally almost wholly grayish pollinose, dorsally 
with dull, velvety-black pollinosity on which stand out con- 
spicuous white pollinose markings as follows: a median triangle 
on the hind margin of tergites 2 to 6, largest on 3 and 4 where 
they are about as high as wide and reach the anterior margin of 
the tergite, slightly smaller on 2 and 5 where they occupy half 
or less of the length of the tergite (triangle of tergite 2 wider 
than long), very small on 6; a narrow streak at hind margin on 
each side of tergites 2 to 6 (widest on 2) extending to near the 
median triangle, from which it is, however, sharply divided; in 
addition a similar, but broader streak on each side at anterior 
margin of tergite 2, leaving about the median third free and not 
connected on the sides with the streak of the hind margin ; venter 
with long, white hairs; tergites with shorter, mostly black hairs, 
