SYNOPSIS OF NORTH AMERICAN SYRPHID^. 23 



formly metallic green or black. Eyes contiguous in tbe male, pilose. 

 Thorax short, broad. Scutellum with an acute margin, without tuber- 

 cles or spines. Abdomen about three times as long as the thorax, in its 

 middle as broad ; the segments shallowly grooved transversely. Legs 

 not very strong, the hind femora sometimes a little thickened ; hind me- 

 tatarsi often somewhat thickened, always shorter than the remaining 

 joints together. Wings rather short and broad; marginal cell open, 

 third vein nearly straight, or gently convex, anterior cross- vein before 

 the middle of the discal cell, first posterior cell briefly or rather long 

 petiolate, the vein at outer part of first posterior and discal cells often 

 bent or augulated. Type of genus, P. noctiluca, Linue. 



TABLE OF SPECIES. 



1. — Abdoineu with a basal interrupted yellow fascia 2 



Abdomen uniformly black 3 



2. — Wings with a brown spot in the middle festiva 



Wings without a brown spot in the middle femoralis 



3. — Third joint of antenna) at least twice as long as wide 4 



Third joint scarcely twice as long as wide, or rounded 5 



4. — Third joint of antennje elongate ; hind metatarsi much thickened ; last section of 

 fourth vein bent near its middle pulchella 



Third joint elliptical, hind metatarsi but slightly thickened; last section of 



fourth vein bent at its antepenultimate third pistica 



5. — Black pilose nigripilosa 



Chiefly light pilose 6 



6. — Wings with a brownish cloud 7 



Wings without such cloud pisticoides 



7. — Abdomen chiefly light pilose albipilosa 



Abdomen chiefly black pilose puella 



For additional species, north of Mexico, see descriptions. P. puhes- 

 cens, P. modesta, P. calcarata, P. salax, P. nigriharba, P. fraudulenta. 



Pipiza pubescens. 



TrUjhiphus puhescens Loew, Centur., iv, 61. 



Habitat. — Wisconsin (Lw.)! 



$ . Black-green, clothed with rather long dilutely lutescent pile. 

 Hind tibite black pilose; the knees, base of front tibiae, and the tarsi, 

 except tbe tip and metatarsi of the front and hind pairs, yellowish. 

 Length, 4'"'". 



Black-green, shining, wholly clothed with rather long pile. Pile of 

 the face white ; of the front near the antennae very dilutely lutescent ; on 

 the angle of the front above, and on the vertex, black. Antennae black, 

 rather long, the third joint oblong, below obscurely reddish. Pile of 

 the thorax and scutellum lutescent. Pile of the abdomen lighter than 

 on the thorax, near the end whitish, on the posterior margins of the 

 second and third segments black. Legs greenish-black, pallidly pilose, 

 the hind tibiae black pilose above. Knees and base of front and middle 

 tibiae dilutely lutescent ; front tarsi black, with the first joint fuscous 



