NORTH AMERICAN DIPTERA. 
373 
open or almost closed in border just at or very slightly before tip of wing; 
fourth vein curved at bend, without stump or wrinkle! hind cross-vein curved, 
more or less sinuate, nearer bend of fourth vein; tegulse whitish, tinged with 
pale yellowish ; halteres yellowish. Length 5.5 mm. ; of wing 5 min. 
De.scribed from two S specimens from Mr. Chas. Robertson, Cai-- 
linville, 111. This species approaches very closely the genus Cenosoma 
V. d. Wulp, but is, I think, better referred to Clytia. 
ATR0PH01»0I>.4« n. gen. 
Form rather narrow ; head and thorax of equal width, abdomen 
at widest somewhat narrower. Eyes rather thinly, short hairy, aji- 
parently more thickly so on lower portions. Front at vertex about 
one-third the width of head, of S slightly narrower; face of 9 
three-fifths the width of head, of S one-half the width of head ; 
frontal bristles descending in a row to the lower border of the eyes, 
almost to the vihrissje ; a long bristle at each vertical angle directed 
backward and a little inward, next frontal bristle directed ujiward 
and backward, the following ones directed forward and down- 
ward. Both sexes (?) with two orbital bristles on each side. Sides 
of face moderately w'ide, widening towards base of antenufe, with 
some minute short bristly hairs on anterior portion extending up- 
ward among the bristles on the front ; cheeks wide, fully one-half 
the hight of the eye, very short antero-posteriorly, with a few vei\y 
fine hairs, and some bristles on lower and lateral borders ; vibrissae 
decussate, inserted a little above the oral margin ; face strongly re- 
ceding ; facial ridges bare, only one or two bristles above vibrissae. 
An ten me shorter than the face ; first joint short, second a little longer, 
third more than four times the length of the second, very narrow, 
linear, the posterior apical corner rounded ; arista distinctly 3-jointed, 
thickened more than half its length, clothed with short and delicate 
])ubescence, second joint short, not much longer than wide. Pro- 
boscis short, not longer than hight of head, more or less fleshy, la- 
bella developed; palpi filiform, hardly thickened at tip. Scutellum 
with an apical decussate pair of inacrochsetae, and a longer lateral 
one directed outward and extending to about the middle of the sec- 
ond abdominal segment. Abdomen ovo-conical, the first segment a 
little narrowed and somewhat abbreviated ; macrochsetie only mar- 
ginal, except on last segment. Legs rather elongate ; anterior claws 
and pulvilli exceedingly small, minute, those of middle and hind 
feet well developed and distinct, but short and small. Wings with a 
\Tpo(j>o': (atrophied) -f- wou? (foot). 
