!944] Studies on Syrphid Flies 29 
angular spot on the upper part of the face and again on the lower 
part of the face opposite the tubercle. The face in ground color is 
brilliantly shining, metallic black, with perhaps a faint bluish 
luster. On either side of the midline there is a prominent, ven- 
trally connected, violet stripe, its margin golden inside and out. 
These stripes are rather widely separated over most of their 
length; their outer margins are lined by a thin stripe of whitish 
pubescence. Lower half of face sparsely white pubescent and 
diagonally striate opposite the tubercle; the middle of the face is 
cut by four shallow grooves, the outer ones less distinct ; the pro- 
file of face above the low tubercle is perfectly straight. The first 
and second joints of antennae are nearly equal in length; light 
brownish-yellow; third joint missing. The eyes are bare. Pile of 
face and front light brownish-yellow, of the vertex darker. 
Thorax: very convex, shining metallic black; seen from behind 
there are a pair of brownish, pollinose, median vittae which run 
half-way down the posterior part of the mesonotum. There are 
suggestions of a fourth pair of such vittae lying some distance 
from the others on the lateral part of the mesonotum. There is a 
low but well developed, rounded bump in the middle of the an- 
terior lateral corners of the thorax lying diagonally from, the 
humeri. Squamae dark brown with dark brown fringe; halteres 
pale. Scutellum broadly rounded, brilliantly metallic, with two 
or three subterminal, transverse, faint, ripple-like depressions. 
Pile of thorax and scutellum pale, the ventral fringe long. Ab- 
domen: long and slender, rather flattened, sides almost parallel, 
end of the third segment barely wider than base of the abdomen. 
First segment shining metallic black, second shining on the basal 
two-fifths with a brassy or golden-brown appearance; opaque, 
dark sepia-brown on almost all of the remaining segments and 
quite to their posterior margin. Located near the base upon the 
sides of the second segment, not reaching the anterior corners and 
covering about one-half the length of the segment there is a shal- 
low, diffuse, brownish-yellow spot; in some specimens it extends 
inward for a greater distance. Third segment with a pair of large, 
square, light brownish-yellow spots occupying the base, the en- 
tire anterior corners and the sides for one-half the length of the 
segment; their medial surfaces are just a little cut-away and 
diminished on their posterior surfaces; remainder of this segment 
opaque, dark sepia. Fourth segment with a pair of similar spots, 
slightly smaller, barely darker, and a very little closer together; 
