SUBFAMILY CALLIPHORINAE PAB 
two or three; posthumeral bristle present; preintraalar bristles 
one or two; preacrostichal bristles two; predorsocentral bristles 
three; presupraalar bristle one; notopleural bristles two; pro- 
sternum flat, bulging anteriorly, wide, laterally and posteriorly 
setose; postalar declivity setose in center; tympanic pit bare in 
center; tympanic ridge with a few weak hairs; postalar bristles 
two; postacrostichal and postdorsocentral bristles three; post- 
intraalar bristles two; postsupraalar bristles three; spiracles 
rather small; scutellum with one discal bristle, three lateral 
bristles and apical bristles absent. 
Legs with middle femur having one to three anterior bristles 
near middle, about five anteroventral bristles in a row toward 
base, and a posteroventral row of bristles which are close-set 
toward base; middle tibia with one ventral bristle near apical 
third; hind femur with anteroventral row of about six bristles 
from basal third to apex, about three ventral bristles toward 
middle, and rows of strong dorsal and posterodorsal bristles. 
Wing with single or double costal spine which is small but 
obvious; anterior cross vein at middle of second section of fourth 
vein. 
Abdomen green to blue green, rather conical in male, ovate in 
female; ventral membrane not exposed; each segment with mar- 
ginal bristles, these weak on first segment. Fifth sternite of 
male (pl. 26, A) long, divided, protruding ventrally and obvious 
in profile, the genital segments large, globose, first segment with 
row of long but weak marginal bristles. 
Genotype, Steringomyra aldrichia Shannon. 
The genus Steringomyia Pokorny does not occur in North 
America. Although the name has been used frequently in the 
North American literature, the genotype of Steringomyia (styli- 
fera Pok.) is quite different from the species included here under 
Acronesia. 
The species of Acronesia are most closely related to the Pale- 
arctic species belonging to the genus Acrophaga, but, unlike 
these, they lack a row of marginal bristles on the first abdominal 
segment, they do not have hair on the tympanic pit, and they 
have but three lateral scutellar bristles. 
The name Cynomyia flavipalpis Macquart (1851, p. 209) refers 
to a species unknown to me. The type, a female which cannot 
be found, was stated to be from ‘‘Terre Neuve,’’ probably New- 
foundland. Shannon (1926, p. 133) referred the name to Ster- 
ingomyia, but he did not see the type. The description seems to 
apply toa species of Acronesia, but I am unable to identify it. 
