32 Bulletin of the Brooklyn Entomological Society Vol. XIII 
(leucostoma), the anterior 2 pairs of postsutural dorso-centrals 
much more reduced in size, and the pteropleura pubescent. 
Key To SPECIES. 
1. Halteres yellow 
Halteres blacks 555 diesealerscawe cio Ge Ga OER a ee 3 
2. Fore tibia with an antero-ventral bristle; glossy blue-black species 
with apical dorsal abdominal segment white pruinescent, 
ciliata Fabricius. 
Fore tibia without an antero-ventral bristle; dull black or yellowish 
species, without!’ conspicuous white pruinescence on apical seg- 
NON la SOM MIO CO OM OOOD OOO HOODOO UG OI MOOaG don boDSoo Od 08 2a 
2a. Opaque grayish black species. with black legs and palpi, irritans Fallen. 
Thorax gray, abdomen yellowish at base; legs and palpi yellow, 
succeedens Stein. 
3. Mid tibia with a strong ventral bristle about middle 
MOG! thle, Gnome jyemineel Jorisle .ccogaccuacacastobocconbsocenuse 5 
4. Fore and mid tibize each with a short antero-dorsal bristle; hind 
femora with a series of short hairs at base and apex and 2 long 
fine hairs, one at one third and the other at two thirds from base; 
ventral bristle on mid tibia much beyond middle. .militaris Meigen. 
Fore and mid tibize without antero-dorsal bristle; hind femora without 
the above-mentioned hairs; ventral bristle on mid tibia before 
TOU UG (GH emer en einai, HAMM P SIN nr: GR BL Mogi uN cy A a ie scambus Zetterstedt. 
co Miditibies withva «bristle onyantentor Side ..7.).-65 eee 6 
Mid tibia without a bristle on anterior side .....................- 8 
6. Mid tibia with 2 bristles and a series of short setule on antero-dorsal 
surface; dorsum of thorax opaque gray with 3 broad brownish 
Ritts 3 ee Meaaliag san araAun ie Wear debonair a aioe eens rae palaestrica Meigen. 
Mid tibia with 1 bristle on antero-dorsal surface; dorsum of thorax 
Shimme distinctly quadnivattatesanterionhy, 9. see ose eee 7 
7. Ocellar triangle grayish, the region immediately surrounding ocelli 
polished black; mid femora without long bristles at base ventrally, 
dentipes Fabricius. 
Ocellar triangle shining black, only the posterior lateral angles gray 
pruinose; mid femora with several long bristles on antero- and 
DOSS ArnsMocal oles ake HGS ssaeencucocescouee hought Malloch. 
8. Hind tibia with 1 bristle near apex on postero-dorsal surface; ocellar 
triangle, unless abraded, with dense gray pruinescence so that it 
appears almost entirely opaque ...................armipes Fallen. 
Hind tibia with a bristle at or beyond middle on postero-dorsal sur- 
faces addition ton thle One mleaiy tap exams seit iat eieanal 9 
9. Presutural acrostichals consisting of 2-3 pairs of short stout bristles 
and a few interspersed short setule ................------.-.. 10 
Presutural acrostichals consisting of from 4 to 6 series of short setu- 
