SYNOPSIS OF NOKTH AMERICAN SYRPHID.E. 57 



2.— Front tibiie of the male, on the inner side toward the end, somewhat concave, 

 the outer angle produced into a lappet-like process ; yellow spots on the 

 abdomen in both sexes very large, leaving only a median stripe and cross- 

 bands ; hind femora and tibia? yellow quadratus 



Front tibite of the male gently and evenly convex on the inner side, the tip 

 on the outer side less produced, more angular ; spots of abdomen smaller, 



hind legs chiefly black ** 



3._irront femora in the male with a row of five to seven long bristly hairs; second 

 abdominal segment with large, the fifth with small yellow spots . . . 



chaetopodus 



Front femora without such bristles ; second segment of the abdomen in both sexes 



with a small rounded spot on each side, fifth segment in the male without 



yellow hyperboreus 



For other species, see description. 



Platychirus quadratus. (Plate III, figs. 10, 10 a.) 



Scm-a quadrata Say, J. Acad. Phil., iii, 90, 4, Compl. Wr., ii, 79. 



Sp-phitt quadratus Wiedemann, Auss. Zw. Ins., ii, 135, 32. 



Syrphus fuscanipenms Macquart, Dipt. Exot., 5" Suppl., 95, 58. 



I'latychirm quadratui^ Osteu Sacken, Cat. Dipt., 122. 

 Eahitat. — Eastern, Middle and Pacific States! 



(^ , 9 . Length, 7'"'". Face deep shining green, thickly covered with 

 yellowish pollen; in profile a little receding, tnbercle very little promi- 

 nent. Antenntie brownish black. Frontal triangle yellowish pollinose 

 and with black pile; front in female shining, with a somewhat coppery 

 reflection, i)ollinose on the sides below, and dilated inwardly near the 

 middle. Thorax deep shining metallic green ; plemse with whitish or 

 grayish pollen IScutellum like the thoracic dorsnm. Abdomen with 

 three large pairs of qnadrute, orange yellow spots, leaving a longitudi- 

 nal stripe and three cross-bands shining black, which in some speci- 

 mens are slender, brown, or even obsolete; in the female the black 

 cross-bands are often dilated in the middle, and narrowed on the sides; 

 the fifth segment with a median black stripe, dilated behind, or wholly 

 orange colored ; sixth segment in female small, reddish yellow ; hypo- 

 pyginm shining greenish black. Legs reddish yellow; the first and 

 last two joints of the hind tarsi black ; the hind tibiie sometimes with 

 one or two blackish rings. In the male the front tibiae are gradually di- 

 lated, convex on the outer border below, gently concave on the inner 

 side, the outer angle below produced downward ; tarsi dilated, grad- 

 ually narrowed from base to tip ; the hind metatarsi in the male also 

 thickened. Wings with a brownish tinge across the middle. 



Numerous specimens from ^sTew Enj«land, Kansas, California, &c. 



Platychirus hyperboreus. (Plate III, fig. 12.) 



S(/»7>/fH.s luiperhorens Staeger, Groenl. Autl., 362, 30. 

 Scifia hyperlorca Holmgren, Ins. Nordgroenl., 100. 

 Plafi/cheirus hyperboreus Staeger, Kroj.Tijds., N. Rakke, i, 346. 

 Eahitat.— GreauVdna (Stager), New York (O. S.), Colorado, Pennsyl- 

 vania, White Mountains! 



$. Length, 8 to 9">™. Deep shining metallic green. Face rather thickly 

 covered with yellowish gray pollen, leaving only the tubercle and the 



