SYNOPSIS OB NORTH AMERICAN SYRPHID^. 233 



rata, but it differs especially iu the color of the coxa^, which iu the lat- 

 ter are black. INIiuor differeuces are that in X.femorata the wiugs are 

 more uniformly colored, less tinged M'ith brown on the distal half, the 

 stigma pnler, etc." 



Original description, compared with the type specimen iu the Museum 

 of Comparative Zoology at Cambridge. 



Xylota chalybea. 



Xiiloia ehaliihea Wiedemanu, Auss. Zwei. Ins., ii, 98. 



^fl&«f«/.— Pennsylvania, Virginia ! Illinois (O. R.). 

 S . Length, 12™"'. HeM and antennae black, tbe face lightly dusted 

 on the sides. Dorsum of thorax violet steel-black, with short black 

 pile; inner sides of the humeri with a distinct silvery spot; pleuraj 

 black. Abdomen steely blue black, with white pile on the sides in front. 

 Legs wholly black, with black pile ; hind femora much thickened, hind 

 tibij© arcuated and terminating in a spur; hind cox;t3 without tubercle 

 below. Wings blackish brown, less intense behind. 



Two specimens. The species will be easily recognized by the entire 

 ^abseiice of yellow in its color, by the dark wings, etc. 



Xylota obscura. 



Xi/lota ohscura Loew, Centur., vi, 55. 



Hahitat.—lled Eiver of the North (Lw.), Oregon, California! 

 9 . Length, 10""". Head black, front considerably prominent, and the 

 face moderately excavated. Antennae rather large, tirst two joints 

 black fuscous, third reddish-ferruginous, rounded, arista wholly black. 

 Thoi ax obscurely bronze-green, no white poUinose spot near the humeri. 

 ScutelUiui of the same color. Abdomeu rather broad; first segment 

 black, shining ; second segment, except two large, subtriangular, shin- 

 iug bronze, whitish jtilose spots, black, black pilose, and sub-opaque ; 

 third segment with similar spots coalescing into a fascia; fourth seg- 

 ment wholly shining metallic, the posterior margin rather more blackish ; 

 fifth segment shining black. Venter- wholly scoriaceous black. Legs 

 black, hind lemora slightly thickened, base of all the tibiaj dilutely lutes- 

 cent, the tip of the hind tibiae not produced into a tooth, first two joints 

 of the four from tarsi reddish-ferruginous, or reddish fuscous, hind tarsi 

 wholly black, below pallidly tomeutose. Wings sub-hyaline, stigma 

 fuscous, anterior cross-vein long and much oblique.— Translation. 



Xylota barbata. 



Xylofa harhata Loew, Ceutur., v, 40. 



Habitat.— ^itksb (Lw^). 



9. Length, IC"™. Head broad, black. Front moderately projecting, 

 black pilose. First two joints of the antennae black, third blackish- 

 brown, sub rotund; arista black. Face moderately excavated, white 

 l)oninose. Pile on the posterior orbits below white, rather longer than 

 usual iu Xylotse. Dorsum of thorax obscurely coppery metallic, mod- 

 erately shining, white pilose. Abdomen rather broad, blue black, sub- 



