500 PROCEEDINGS OF THE ACADEMY OF [Sept., 
and covered with a dense whitish pubescence. Head light gray with 
a distinct dark brown median vitta. 
Mesonotal praescutum dull brownish gray, the middle vitta 
broadly divided by a dull gray median stripe which is much broader 
than the brown margin' enclosing it; lateral stripes rarely distinct; 
scutum dull brownish gray, the lobes a little more brownish medially; 
scutellum and postnotum yellowish gray with a narrow dark brown 
median stripe. Pleura light gray, the dorsal pleurites more yellowish. 
Halteres rather elongate, the stem somewhat pale, the knobs large, 
dark brown. Legs Avith the coxse dull light yellow covered with a 
sparse white pollen; trochanters dull yellow; femora dull yellowish 
brown, the apices indistinctly darker brown ; tibiae brown, darkened 
at the apex; tarsi brown. Wings light gray; stigma distinct, dark 
brown; a pale vitreous band before the stigma, interrupted in the 
vicinity of cross-vein r-m; a vitreous spot beyond the stigma in cell 
2nd R,. Venation as in Plate XVII, fig. 18. 
Abdomen dull yellow, quite bright in places; a dorsal brown stripe 
which is almost continuous, interrupted only by a narrow silvery 
caudal margin to the individual segments; on the seventh to ninth 
segments this band is in some specimens more broadened out to 
cover the segment or nearly so; an interrupted brown stripe on the 
sides of the tergites, this consisting of a large brown blotch about 
midlength of each segment, on the seventh segment often becoming 
confluent with the dorsal stripe; sternites dull yellow. Male geni- 
talia (see Plate XVIII, fig. 39) with the ninth tergite (see Plate XIX, 
fig. 56) small, subquadrate, much broader than long, the caudal 
margin with a deep V-shaped notch whose edge is chitinized and 
microscopically denticulate. Ninth pleurite incomplete, the pleural 
suture very short, the pleural region cylindrical, produced caudad 
and slightly entad as a long, slender lobe which is subspatulate; 
outer pleural appendage a very slender, elongate, cylindrical lobe, 
pale, with scattered black hairs; this appendage is directed dorsad 
with its tip close to the caudal margin of the ninth tergite; the 
second appendage (see Plate XX, fig. 71) is flattened, deeply bilobed, 
the outer lobe subcylindrical to somewhat flattened, chitinized 
especially along the margin; the inner lobe is very extensive, flattened, 
pale, with a somewhat })lunt point directed laterad, the tip of the 
lobe with numerous hairs; third pleural appendage consisting of a 
compressed, flattened lobe, directed cephalad and dorsad, the apex 
strongly chitinized, black, divided into two lobules by a deep notch; 
the upper lobule cylindrical, smooth, the lower lobule with a few 
