1917] New Species of Colorado SyrphideB 229 



M . flavoterminata differs from M. Sackeni in that the marginal 

 cell of the former is open and in the latter it is closed. The 

 pile of the fourth and fifth segments in the former is the same 

 color as the thorax, and not blackish as in M. Sackeni. M. 

 flavoterminata differs from M. cimbiciformis in that the males 

 are dichoptic, the pile and color of the abdomen and the brown 

 spot in the wing. 



Mallota palmeras n. sp. 



Length, cT, 11-12 mm. Eyes bare, converging a short distance 

 below the ocelli. Frontal triangle and vertex separated by a distinct 

 transverse suture, frontal triangle with whitish pile, thickly covered with 

 white pollen, a shining brown stripe above the antenna?. Face deeply 

 concave from the base of the antennee to the tip of the tubercle, slightly 

 receding, thickly covered on the sides and below the antennse with 

 whitish pollen, leaving a black bare, median, shining stripe, about one- 

 fifth the width of the face, pile whitish, and rather long on the sides; 

 vertical triangle slightly darker than the frontal, and with moderately 

 thick long white pile. Cheeks shining black. Antennse brownish black, 

 situated on a brownish truncated process; third joint lighter, rounded 

 and covered with whitish pollen; arista reddish. Dorsum of thorax in 

 ground color, black, moderately covered with whitish pollen which gives 

 the appearance of two light colored abbreviated longitudinal lines. 

 Pile abundant, short, and light yellow. Scutellum yellowish, shining, 

 with fine yellowish and whitish pile. Abdomen long, narrow, obtusely 

 conical, of a dark-brownish color, shining, and with light colored pile; 

 first segment densely covered with white pollen and moderately long, 

 whitish pile; second segment with a pair of brownish, rather indistinct, 

 median transverse triangular spots which reach the lateral margins and 

 are separated medially; the posterior portion narrowly margined with 

 brown. The following segments similar to segment two, but the 

 brownish portion less conspicuous. Legs blackish, with whitish pile, all 

 tarsi apex of hind femora and hind tibiae brownish, a tuft of stout brown- 

 ish hair underneath the apex of hind tibiae, hind femora considerably 

 thickened in the male, arcuate, hind tibise arcuate. Wings hyaline, 

 with a distinct brown spot from the base of the discal cell to beyond 

 the anterior cross- vein. 



Habitat: Two males, one, C. S. Mead, collected on buck- 

 wheat. Fort Collins, Colorado. C. R. Jones, Platteville, Colo- 

 rado, taken on Dichrophyllum marginatum, June and August, 

 1915. 



Xylota nigromaculata n. sp. 



Length, 9, 10 mm.; cf, 8 mm. Head black, front considerable 

 excavated below the antennse, oral margin projecting; face blackish, light 

 pollinose, pile whitish; cheeks black, shining, and white pile; front of 

 female narrowed above, black, with two dashes of light pollen somewhat 



