NORTH AMERICAN DIPTKRA. 117 



little narrowed toward vertex, face somewhat widened ; frontal bris- 

 tles in a single row descending to base of third antenjial joint, two 

 posterior ones on each side strongest, directed backward, witli one or 

 two weak ones between them, others directed inward, decussate; two 

 orbital bristles in % directed strongly forward. Face hardly re- 

 ceding, epistoma hardly prominent ; facial de{)ression about three- 

 fifths width of face, wider below, very shallow ; facial ridges bare, 

 except a bristle or two next vibrissse, but slightly constricted below; 

 sides of face moderately narrow, bare ; cheeks about one-fifth eye- 

 hight, bare except bristles on lower margin ; vibrisste strong, decus- 

 sate, inserted on oral margin. Eyes bare, descending about as low 

 as vibriss£e. Antennae a little shorter than face, first two joints 

 short, third four or five times as long as second, moderately wide, 

 rounded at apex ; arista rather long, minutely pubescent, thickened 

 slightly on basal third, apparently only 2-jointed, basal joint short. 

 Proboscis somewhat less than twice as long as bight of head, slender, 

 nearly straight below geniculation, labella slightly developed ; palpi 

 slender, thickened at tip. Thorax about as wide as head ; scutellum 

 with a straight subapical pair of macrocha?tie reaching almost to ba.^^e 

 of third abdominal segment, a shorter lateral pair, a weak subdiscal 

 pair, and an extremely weak decussate apical pair. Abdomen rather 

 elongate-conical, about as wide as thorax at base, first segment some- 

 what shortened, especially above ; macrochajtaj only marginal ; hy- 

 popygium of % exserted. Legs elongate, only finely bristly, meta- 

 tarsi nearly as long as following joints together; claws and pulvilli 

 very short in % . Wings a very little longer than abdomen, without 

 costal spine (spine microscopic), third vein bristly part way to small 

 cross-vein ; apical cell well opened immediately before tip of wing ; 

 fourth vein curved at bend, apical cross-vein bowed in ; hind cross- 

 vein nearly straight, a little oblique, but little nearer to bow of 

 fourth vein than to small cross-vein. Type, S. robertsonii u. sp. 



Siplioolytia robertsonii u. sp. S-— Eyes light brown, frontal vitta 

 yellowish brown ; sides of front silvery cinereous ; face and cheeks silvery-white ; 

 anterior pair of ocellar bristles strongest, directed forward and strongly outward ; 

 anteunsB blackish, first two joints and basal portions of third reddish yellow, 

 second joint with a bristle on front edge, arista black ; proboscis black, whitish 

 at base, palpi light reddish yellow; occiput cinereous, gray-hairy below, black- 

 bristly above. Thorax cinereous, with four rather heavy blackish vitta;, the 

 outer ones interrupted at suture; scutellum cinereous. Abdomen blackish, sil- 

 very-white pollinose, the sides of first and second segments and whole of anal 

 segment yellowish rufous; second segment with a lateral macrochaHaand a median 

 marginal pair, third and anal segments with a marginal row of six or more mac- 



TRANS. AM. ENT. SOC. XIX. MAY, 1892. 



