SUBFAMILY POLLENIINAE 341 
bristles three or four; postintraalar bristles two; postacrostichal 
bristles one to three; spiracles small; lateral postscutellar plates 
setose; scutellum with under surface bare in center and with 
four strong lateral bristles. 
Legs with posterior coxae bare posteriorly; fore tibia with two 
posterior bristles; fore femur with dorsal, posterodorsal and post- 
eroventral rows of bristles; posterior femur with anterodorsal, 
anteroventral and posteroventral rows of bristles; tarsi as long 
as the tibiae; claws and pulvilli as long as apical tarsal segments. 
Wing without strong costal spine; subcostal sclerite without 
setae; fourth vein with angular bend; apical cross vein only 
slightly sinuate; anterior cross vein oblique; posterior cross vein - 
doubly arcuate; seventh vein curved; upper squamal lobe small, 
rounded, bare; lower squamal lobe large, long-ovate, bare. 
Abdomen ovo-conical in male, flattened dorsoventrally in 
female; lateral margins of tergites overlapping sternites; ventral 
membrane not exposed; first segment of scutellar depression not 
extending more than one-third the distance to the hind margin; 
only fourth segment with erect discal bristles; no median mar- 
ginal bristles; third and fourth segments each with a row of long 
and strong marginal bristles. 
Genital segments of male globose. 
KEY TO GENERA AND SPECIES OF POLLENIINAE 
1. Postseutum and scutellum flattened discally, the scutellum 
widened; body with fine tawny-colored crinkly pile or 
hair; presutural preintraalar bristle present; posthumeral 
bristle present (Polleniini) (Holarctic)............... 
tye se Re Ih Pollenia rudis (Fabricius), p. 344 
Postscutum and scutellum convex discally, the scutellum 
not conspicuously widened; body without crinkly hair; 
presutural preintraalar bristle absent; posthumeral bristle 
BUSeiur ey elanocdexrini \eers se ee aL Pes 2 
2. Carina low, rounded, not very apparent (Melanodexiopsis) 3 
Carina high, sharp, reaching at least to base of second an- 
Teluial SOGMeNL: 25. cst e ke we (Melanodexia Williston) 7 
3. Epistoma long,-slightly narrower than clypeus, then widen- 
ing below vibrissae which are high above the oral mar- 
UM, can ga SEAR SE its be ee re oe sae 4 
Epistoma short, nearly as wide as clypeus, and not widen- 
ing much below the vibrissae which are only slightly above 
PHesorslatiaArcins (NEGALCLIO SM), Sire es Ais Pe. oe 
eos Melanodexiopsis idahoensis, new species, p. 357 
