230 Annals Entomological Society of America [Vol. X, 



remote from the eyes; front of the male black, with light pollen; antcnnic 

 short, fuscus, rounded; third joint scarcely longer than broad; arista 

 bare, somewhat basal, reddish brown, lighter at tips; thorax metallic 

 green, with short whitish pile, three dorso-medial cinerous stripes extend- 

 ing the entire length of thorax, the medial one about one-half the width 

 of the others, meta-thoracic portion with additional cinereous stripes; 

 scutellum the same color as thorax, with white pile, thicker and heavier 

 on margin; abdomen bluish black, shining with whitish pile; second 

 segment with triangular, metallic, greenish, shining side spots; legs 

 nearly black, hind femora much thickened, hind tibiae arcuate, reddish 

 at apex, base of all tibiae somewhat lutescent ; front tarsi cinereous, inner 

 margin of middle tibiae with long whitish jjile; wings blackish brown, 

 stigma brown, anterior cross-vein oblique, wholly or jjartially surrounded 

 by a black spot. 



X. nigromaculata differs from X. metallifera to which it is 

 closely related, in that the abdomen of the former is steel blue, 

 shining, and has triangular metallic, greenish, shining side 

 spots on the second segment; while the latter is opaque black; 

 and in that the abdomen of the former does not have the 

 elongated oval spots that occur in the latter. The former has 

 distinctly thickened hind femora and the hind tibiae are arcuate. 

 These characters do not appear in the description of X. metal- 

 lifera. I do not know of any specimens of the latter besides 

 the types and these were unobtainable, so the description was 

 all that was consulted. 



Three specimens, two females and one male, Fort Collins, 

 Colorado. The male was taken by S. A. Johnson at apple 

 blossoms and the two females were reared from pupae taken from 

 an old decaying stump by E. C. Hotchkiss, April 21, 1903. 



The following syrphid could not be exactly placed. In the 

 key, it came nearest to Xylota, but the generic description did 

 not fit, so, for lack of a better name, I have called it Microxylota 

 and the species, robii. 



Two specimens. Fort Collins, Colorado. C. S. Mead, 

 Collector. 



Microxylota n. g. 



Small species, 6.5 to 7 mm., slender, metallic; head hemispherical, 

 slightly broader than thorax; antennae situated on slight conical pro- 

 jection, first two joints short, third more or less oval; arista dorsal, bare; 

 face concave in profile, epistoma slightly projecting; eyes pubescent, 

 contiguous in males; thorax rather large, metallic green; scutellum 

 metallic green, thinned along border; abdomen slightly narrower than 

 the thorax; metallic greenish black, shiny, flattened, sides nearly 



