10. 
WHEELER: ANTS OF THE GENUS FORMICA. 395 
Antennal scapes with erect or suberect hairs................ 4 
Antennal scapes without erect or suberect hairs.............. 5 
Hairs on antennal scapes coarse and clavate. . .cmpexa Wheeler. 
Hairs on antennal scapes delicate, not clavate. 
microgyna Wheeler. 
Border of petiole blunt; head and thorax rich yellowish red. . .6 
Border of petiole sharp and compressed; head and thorax sordid 
erie rediciee a ereehaels . buel. wo enlndiakeel td .. 10 
Gaster black or dark brown, not red at the base.............. dé 
Gasterhbrommetecdimmihie Wasi y bead toc. weil eo ee 9 
Largest workers with the pro- and mesonotum and also the 
ocellar region infuscated. 
microgyna rasilis var. spicata, var. nov. 
Largest workers without the head and thorax infuscated or at 
Mestewith dark ocean Uliana. WY Tht eae 8 
Tibiae with abundant, short, subappressed hairs on their ex- 
sensor Surtaces. 2.02.25 "0" microgyna var. recidwa, var. Nov. 
Tibiae without such hairs......... microgyna rasilis Wheeler. 
Erect hairs on head, thorax, and gaster moderately numerous, 
usually lacking on posterolateral corners of head. 
difficulis Emery. 
Erect hairs more abundant and longer, especially on the front, 
gula, and thorax, present on posterolateral corners of head. 
difficilis var. consocians Wheeler. 
Posterior portion of head, a spot on the pronotum and one on 
the mesonotum dark brown or blackish... ... adamst Wheeler. 
Infuseation of head and thorax more restricted, frontal area 
smoother and more shining...... adamsi var. alpina Wheeler. 
Females. 
Gaster reddish yellow like the head and thorax............... 2 
meeerueamr or Diddle ela ee he ede ot ee nes se 3 
Tibiae without long, oblique hairs............ difficulis Emery. 
Tibiae with long, oblique hairs. . difficilis var. consocians Wheeler. 
Gaster smooth and more or less shining, finely and sparsely 
(Loy 0b Sse sad expleiapelicin ue la lca nl gma aerials dats carr 4 
Gaster opaque, with denser, longer pubescence.............-. 6 
Antennal scapes without erect hairs. . microgyna scitula, subsp. nov. 
Amtcimal seapes with erect hairs... ee ee 5 
