1915.] NATURAL SCIENCES OF rHILADELPIIIA. 489 
Male. — Length, 15 mm.; wing, 16.3 mm. 
Frontal prolongation of the head long, pale brownish yellow, \\dth 
a sparse whitish bloom. Palpi almost black. Antennae with the 
three basal segments dull yellow, the remainder of the flagellum 
uniformly dark brownish. Head light gray with a subimpressed 
dark brown median vitta. 
Pronotum pale, a little darkened on either side of the middle line. 
Mesonotal prcescutum dull gray with darker brown vitta), the median 
stripe divided into two by a very broad line of the ground color; 
lateral stripes indistinct; scutellum and postnotum much clearer 
gray. Pleura with the mesopleura clear light gray, the dorsal 
membrane and the metapleura dull yellow. Halteres yellow, 
passing into dark brown on the knob. Legs with the coxse and 
trochanters dull light yellow, the former sparsely whitish pollinose; 
femora yellow, darkened at the apex; tibiae and metatarsus yellowish 
brown, the segments a little darkened at the apex ; remainder of the 
tarsi brown. Wings as in Plate XVI, fig. 12. 
Abdomen with the sides of the first two tergites bright yellowish, 
the dorso-median line and the remaining tergites brown; segments 
with a broad lateral and a narrow caudal pale margin; hypopygium 
reddish; sternites brown, more yellowish laterally; segments three 
to five with a conspicuous caudal margin of the same color. Male 
hypopygium with the ninth tergite (see Plate XIX, fig. 51) rather 
sriiall, subquadrate, narrowed apically, the caudal margin with a 
broad V-shaped notch whose edge is provided with a few chitinized 
tubercles; a shallow dorsal median groove. Ninth pleurite incom- 
plete, indicated beneath, situated high up on the caudal face of the 
ninth sternite so that its inner dorsal angle about touches the ninth 
tergite; the caudal end of the pleurite is produced caudad into a 
flattened, subspatulate lobe (see Plate XX, fig. 67), in this suggesting 
the condition found in T. macrolahis, though to a A^ery much lesser 
degree; a few scattered black hairs at the base of the sclerite on the 
outer side, outer pleural appendage a subcylindrical fleshy lobe with 
numerous long pale hairs; inner pleural appendage a flattened lobe 
which lies across the genital chamber, this bearing a sharp spine 
behind directed outward and a rounded concave lobe directed 
dorsad, the two being portions of a high dorsal crest of the appendage; 
cephalic arm of the appendage hidden beneath the ninth tergite. 
Ninth sternite with a deep V-shaped notch beneath, the ventro- 
median area pale, submembranaceous; at the lateral end of this 
notch and just below the pleurite is a papillose lobe directed inward 
