NORTH AMKKICAN DIPTERA. 
369 
frontal vitta but little darker, occupying one-balf width of front, cleft before 
and behind; frontal bristles descending only to base of third antennal joint; a 
pair at each vertical angle, the inner longer one directed backward, the outer 
shorter one directed outward and backward ; next frontal bristle directed out- 
ward and backward, next backward, rest inward, but not decussate; two orbital 
bristles on each side; two pairs of ocellar bristles, posterior pair shorter, erect, 
directed a little backward and outward, anterior pair long, appressed, directed 
forward and strongly outward; face and cheeks silvery-white; sides of face 
extremely narrow, bare; cheeks rather narrow, restricted posteriorly beneath 
the eyes, bare with bristles on lower border; face nearly perpendicular, epistoma 
rather prominent; vibrissfe inserted a little above the oral margin, not decussate, 
a short bristle above and a longer one below them ; antenn* quite as long as the 
face, first two joints light yellowish brown, second joint a little longer than first, 
very short bristly before ; third joint blackish, over three times as long as .second, 
widened, convex behind, straight before, posterior apical corner rounded ; arista 
brownish, thickened more than half its length, minutely pubescent, distinctly 
3-jointed, second joint strongly elongate, sometimes geniculate; proboscis very 
long, bristle-like, twice geniculate, apical portion folded back, light brownish 
yellow, blackish at distal geniculation,labella not developed; palpi rather slender, 
thickened at tip, yellow, black-hairy, with two black bristles on under surface 
before tip ; occiput golden-cinereous, black -hairy, with a fringe of bristly hairs 
on orbital margins. Thorax and scutellum golden-cinereous, clothed with black 
bristly hairs, stouter posteriorly; thorax with a median pair of faint cinereous 
vittee, becoming obsolete at suture; humeri and pleurte concolorous; apical pair 
of scutellar macrochsetaj decussate, reaching middle of second abdominal seg- 
ment, two lateral macrochsetse on each side. Abdomen oblong-oval, first joint 
scarcely shortened ; color deep golden, with an irregular, median, dark cinereous 
vitta, widening posteriorly on segments two and three, nearly obsolete on seg- 
ment four, all segments covered with short, black, appressed hairs ; macrochteta? 
only marginal ; first segment with one lateral macrochfeta ; second with a me- 
dian pair and one lateral one (frequently another macrochseta-like bristle, giving 
the appearance of a lateral pair) ; third with six macrochsetfe, a pair on each 
side the median pair; anal with four macrochtetie above; venter golden. Legs 
light reddish golden, except tarsi which are blackish ; black-hairy, tibite bristly, 
femora slightly so; claws and pulvilli short. TEmgs grayish hyaline, slightly 
longer than abdomen, with costal spine, third vein spined as far as small cross- 
vein ; apical cell ending at tip of wing, narrowly open ; fourth vein bent in a 
gentle curve, without stump or wrinkle; hind cross vein slightly nearer to the 
small cross-vein than to bend, or about in the middle; te^ulse nearly white, 
halteres yellowish. Length 4 mm. ; of wing 3 mm. 
Described from two sjfecimens received from Mr. Chas. Kobertson, 
Carlin ville. 111. 
PII.4$$10CL.IST.4 * n. gen. 
Differs from Schiner’s description of Clista only as follows; Me- 
tallic dark green species. Eyes bare; face a little receding; sides 
of face very wide, fully as wide as facial depression, covered with 
Phasia + Clista. 
(47) 
TRANS. AM. KNT. SOC. XVIII. 
DKCEMBEE, 1891. 
