6 MISC. PUBLICATION 305, U. 8S. DEPT. OF AGRICULTURE 
tion was obtained by using a micrometer disk ruled in squares and 
coordinate paper ruled with pale blue lines. All of the figures repre- 
sent an enlargement of about 7.7 diameters. 
The Genus MERYCOMYIA Hine 
Merycomyia Hine, Ohio Nat. 12: 515-516, 1912. (Genotype, Merycomyia gemi- 
nata Hine=M. whitneyi (Johnson).) 
This genus is treated separately because a study of all available 
material convinces the writer that the genus is pangoniine rather 
than tabanine, although Johnson (45) placed the type of the genus in 
Tabanus and Hine, in describing the genus, states, “* * * no 
spurs at apex of hind tibia, * * *.” The types of Merycomyia 
geminata are apparently lost, but Hine admitted the identity of 
geminata and whitneyi and there 1s no question but that they are the 
same. The type male of whitneyi shows extremely small hind tibial 
spurs; the allotype has one distinct spur, the others being broken 
off. Two other specimens show the spurs small but distinct. Edward 
S. Thomas examined the type of W. mixta Hine for the writer and 
found spurs present in this species also. 
In addition to the presence of spurs, the presence of well developed 
ocelli and the shape of the female frons and palpus are typically 
pangoniine. Since only three or four divisions are to be found in 
the antennal flagellum, the genus falls in neither half of the first 
couplet of Brennan’s (7 ) key to the genera of Pangoniinae. This 
and other characters seem clearly to separate it from all described 
genera of Tabanidae. 
KEY TO THE GENERA OF NEARCTIC TABANINAE 
1. First antennal segment considerably longer than thick; frons of 
female widened below, broader than high, with a velvety-black 
spot to each side at angle made by eye and subeallus; third 
antennal segment with four divisions; wing gray, with small 
Whitevmaculavlons 2 se ee Haematopota Meigen, p. 7. 
First antennal segment usually scarcely longer than thick; frons of 
female not broader than high, without velvety-black spots; third 
antennal segment usually with five divisions; wing pattern, if 
any,’ OUNerwises oes SENS To de eee 2 
2. Eye bare; subcallus very swollen and shiny; genae denuded; dorsal 
angle of third antennal segment small and blunt; wing at least 
partially» blackened 22-2 soem ee ee a eee 3 
Without above combination of characters; if the subcallus is enlarged 
and denuded, the eye"is densely pilose22i.: Devs 2 ee ee aa 
3. First antennal segment swollen, at least below; apical half of vein 
R, turned abruptly forward; wing, at least anteriorly, blackened, 
with a crescent-shaped, hyaline apex; tibiae somewhat swollen 
Bolbodimyia Bigot, p. 10. 
First antennal segment not noticeably swollen; vein R;: not turned 
abruptly forward; apex of wing not hyaline; tibiae not swollen 
Whitneyomyia Bequaert, p. 11. 
4. Third antennal segment with no dorsal angle; frons of female very 
narrow, the median callus a very slender line; no _ ocellar 
tubercle; wing with at least a subapical brown spot; eye bare 
Diachlorus Osten Sacken, p. 12. 
Not ‘with this combination of characters <2 sos 2 eee 9) 
5. Basal portion of third antennal segment with a prominent, forward- 
projecting tooth reaching nearly to base of annulate portion; eye 
DIL OSG ics 2 er oa ES Rieti eat Dicladocera Lutz, p. 14. 
