NORTH AMKKICAN DIPTERA. 
877 
DKKPAlVOtil^OSSA* n. }jen. 
Belongs in the Phytoinaj, perhaps in the neighborhood of Myo- 
thyria v. d. Wulp. Tlie arista, however, is distinctly 3-jointed, while 
the peculiar proboscis will at once distinguish it from other genera. 
Body rather narrow ; thorax and abdomen about equal in width, 
the head very slightly wider. Eyes bare ; front and face rather wide, 
from one-third to three-fifths the width of the head ; distance between 
the eyes at vertex and cheeks the same. Sides of face bare, very 
narrow below, gradually widening to base of antennae ; cheeks bare, 
rather narrow, with some bristles on the lower and forward margin ; 
the nearly decussate vibrissae inserted on the oral margin. Frontal 
bristles descending but little below the base of antennae, about to 
base of third joint; a pair of unequal length at each vertical angle, 
the shorter outer one directed outward, the other directed backward ; 
next two frontal bristles on each^side directed backward, remainder 
directed inward ; two orbital bristles on each side directed forward. 
Face receding, epistoma somewhat prominent ; facial ridges bare. 
AnteniRe a little shorter than the face, first joint very short, second 
not elongate, third a little more than three times the length of second 
and somewhat widened ; arista distinctly 3-jointed, thickened more 
than half its length, very short and fine pubescent, second joint not 
elongate. Proboscis quite widely extended, about three times as 
long as hight of head, bristle-like, once geniculate, the distal portion 
sometimes very strongly curved or bowed, usually considerably 
bowed, but sometimes almost straight, labella somewhat developed ; 
j)ali)i filiform, hardly thickened toward tip. An apical and lateral 
pair of scutellar macrochsetje, the former longer, not decussate, and 
reaching a little more than the base of second abdominal segment. 
Abdomen elongate oval, sometimes shorter oval, first segment not 
abbreviated ; macrbchsetae all marginal on segments two to four. 
Legs moderately long, tarsi rather elongate and delicate. Wings 
broad, longer than the abdomen, with costal spine, third vein spined 
only at base; apical cell ending very slightly before the tip of the 
wing, much narrowed on its distal portion, usually clo.sed in the 
border, but often very narrowly open ; posterior cross-vein sinuate, 
in the middle between the small cro.ss-vein and the bend of the 
fourth or slightly nearer the bend, which is rounded and without 
stump or wrinkle. Type, D. lucens n. sp. 
* Apen-ai-r) (sickle) + ykiaaua. (tOIlglie). 
( 48 ) 
TRANS. AM. ENT. SOC. XVIII. 
DECEMBER. 1891. 
