140 DIPTERA OF NORTH AMERICA. 



Gen. IV. mSCOMYZA MEIG. 



The characters of this genus are as follows. Head more or less 

 orbicular, with very sharp borders of the vertex ; second joint of 

 the antenna? unguiculated, the third oblong, with long pectinations 

 of the terminal bristle. Face not keeled, rather convex, receding 

 again towards the edge of the mouth, uneven, on the sides with 

 coarse warts and wrinkled. Clypeus entirely concealed. Abdo- 

 men flat, broad, on account of the shortening of the first segment 

 apparently consisting of four rather equally broad segments. 

 Wings proportionately broad, third and fourth longitudinal veins 

 parallel at their ends. 



There were only two species hitherto known; the following 

 North American species deviates a little by its head not being so 

 strikingly orbicular, and by its abdomen not being so broad, but 

 more flattened. 



1. D. balioptera LOEW. . Nigra, tliorace punctulato, antennis 

 genibusqne rufis, tarsis posterioribus flavescentibus, alis fusco-inaculatis. 



Black, with dotted thorax ; antennae and knees yellowish-red, middle and 

 posterior tarsi yellowish ; wings dotted with brownish-black. Long. corp. 

 0.15. Long. al. 0.14. 



Head shining black, really not so orbicular as in Discom. in- 

 curva, but the vertical border likewise very sharp. Front ante- 

 riorly with two rather flat depressions, placed near each other; the 

 more shining lateral border of the front rather wrinkled. Antennoe 

 yellowish-red, the upper border of the second and third joints 

 a little darker ; the antennal bristle with long pectinations. The 

 middle of the face narrow and rather transversely wrinkled ; its 

 lateral parts with coarse warty wrinkles ; the eyes surrounded 

 with a fine white line. The upper side of the thorax and scutel- 

 lum appear to be dusted with white, but have a rather indistinct, 

 exceedingly fine and close punctuation, leaving only small traces 

 of the white dust. On the pleurae, where the punctuation is more 

 distinct and much coarser, the whitish dust is more visible. Abdo- 

 men black, rather shining, exceedingly flat, narrower than in Dis- 

 com. incurva, the cause of which may be that the upper horny 

 plates of the abdomen are turned down to an unusual extent ; the 

 last segment of the abdomen rather smaller than the preceding 



