SUBFAMILY CALLIPHORINAE 285 
apical portion orange brown, 3.8 times as long as second, reach- 
ing four-fifths the distance to the vibrissa; arista black, with 
black cilia; back of head black, with silvery pollen and with three 
or four sparse rows of postocular cilia and whitish to yellowish 
hair. 
Thorax black, with thin grayish pollen and with suggestions 
of darker dorsal longitudinal stripes which do not extend beyond 
the scutellar suture; pleura lightly dusted with gray pollen; 
hindmost preintraalar, dorsocentral and acrostichal bristles 
before suture by 0.6, 1.4 and 2.4 respectively; sclerites at wing 
base mostly black, preparapteron orange with whitish pubes- 
cence; postparapteron orange brown; prothoracic spiracle with 
orange hair on lower half; scutellum with the under surface 
laterally with fine black hair. 
Legs black, middle tibia with two anterodorsal bristles, one 
near basal third, one near apical third and one posterodorsal 
bristle near apical third. 
Wing hyaline; basicosta black; subcostal sclerite orange 
basally, brown apically, orange pubescent; costal sections 2 to 
6 in the proportion 80:46 :102:105:8; upper squamal lobe with 
black rim; lower squamal lobe with white rim. 
Abdomen dark metallic bluish, tessellated, silvery pollinose 
in most lights. 
Genital segments black, shining, with scattered black setae. 
Internal anatomical features (pl. 27, A and B) as illustrated. 
Female. Head width 14.1; length at antenna 6.6 and at vi- 
brissa 6.7; eye height 6.9; head height 10.1; buecca 0.48 of eye 
height; front at vertex 0.38 of head width, 0.42 at lunule; para- 
faciale 2.1 in width opposite lunule; vibrissae set 2.9 apart; 
third antennal segment 4.2 times as long as second. Legs with 
middle tibia with three anterodorsal bristles. Wing with costal 
sections 2 to 6 in the proportions 84:51:110:51:10. Otherwise 
similar to male except for normal sexual differences. 
Length. 5-9 mm. 
As originally noted by Hough (1899), the number of post- 
intraalar bristles varies from two to three in this species. The 
character is not of apparent value in the further separation of 
segregates of this form. Large specimens usually have two well- 
developed postintraalar bristles, but sometimes one is lacking 
on one side or there is an additional smaller bristle anteriorly. 
Smaller specimens often lack this additional postintraalar bristle, 
and the smallest specimens invariably do. The weakening of 
bristles in this species may also be noted in the accessory ocellar 
bristles and in the lateral bristles of the scutellum. Large speci- 
