132 DIPTERA OF NORTH AMERICA. [PART II. 



Tarsi comparatively long ; fore tarsi scarcely infuscated towards 

 the end, only the last joint brown, the first joint a little longer 

 than the others taken together. Middle tarsi from the tip of the 

 first joint strongly infuscated ; the four last joints together as long 

 as the first one. Hind tarsi entirely black, the first joint a little 

 shorter than the second, the following joints decreasing in length. 

 The cilia of the tegula?, which have a blackish border, are pale. 

 Wings tinged more with brownish than yellowish-gray ; veins 

 rather dark brown ; the last segment of the fourth longitudinal 

 vein, before its middle, only slightly inflected forward. 



Hob. Middle States. (Osten-Sackeu.) 



Observation. It is impossible to mistake A. calceata for the 

 female of one of the two preceding species for the following rea- 

 sons : 



1. On account of the greater extent of yellow color upon the 

 abdomen, which is not so extensive in the females of the species 

 of Argyra as in the males. 



2. ' On account of the black coloring of the whole hind tarsi. 

 It is probable that the coloring of the abdomen of the male of this 

 species resembles that of the male of Leucostola cingulata. 



B. Abdomen entirely cylindrical, without white lustre. 



7. A. cylindrica, n. sp. . Viridis, nitens, abdomine vix obso- 

 letissime albido pollinoso, coxis'anticis pedibusque flavis, femorurn pos- 

 ticorum apice, summo tibiarum posticarum apice, tarsis denique omni- 

 bus inde ab articuli prirni apice nigris. 



Shining-green, the abdomen has scarcely a trace of whitish dust ; fore 

 coxae and feet yellow ; tip of the hind femora, tip of the hind tibiae and 

 all tarsi, with the exception of their root, black. Long. corp. 0.23. 

 Long. al. 0.22. 



Metallic-green, and differing from most of the species of 



by the cylindrical form of the abdomen and the almost 

 entire absence of all dust. Face with a white reflection. Palpi 

 and proboscis brownish-black ; the hair-like cilia of the inferior 

 orbit pale-yellowish. Thorax and scutellum shining, the latter 

 without hairs. Abdomen entirely cylindrical, not stouter about 

 the basis, metallic-green, without any transparent spots upon 

 the anterior segments and covered with a thin, almost impercep- 

 tible, grayish-white dust. Fore coxa3 yellowish, with some very 

 scattered black hairs, and, at the tip, with longer black bristles. 



