2 AMERICAN DIPTERA. 



but uo hairs on the hypopleura. The chsetotaxy of the head varies 

 and will be treated in the description of each species ; but there is 

 a common absence of the ocellar bristles in all genera, and of the 

 frontal bristles in the genus Micropeza ; but the inner and outer 

 verticals are present in all genera. 



MICROPEZA Meigen. 

 lUiger's Magazine, ii, 276, 1803. 



Head somewhat conical, projecting forwards beyond the eyes, and 

 the occiput much swollen posteriorly; the front and cheeks nearly 

 parallel ; antennae short, third joint rounded ; thorax narrow, elon- 

 gate ; abdomen slender; auxiliary vein wanting; discal and second 

 basal cells united ; apical cell narrowed or closed apically. 



PARTIAL TABLE OF NORTH AMERICAN SPECIES. 



1. Apical cell closed and petiolate (for this group, see "Biologia," Diptera, vol. ii, 



p. 364; includes, as far as known, only the Mexican species). 

 Apical cell open, or closed in tbe margin of wing 2. 



2. Hind femora banded near the apex ; small species (4 mm.), Mexican. 



iiigricornis v. d. W. 

 Hind femora not banded ; larger species 3. 



3. Thorax and abdomen rufous; apical cell closed in the margin. 



prodiicta Walk. 

 Thorax, but especially the abdomen, black above ; apical cell open 4. 



4. Posterior part of mesonotum with a large yellow area ; vertex yellow, marked 



with brownish lines; antennae in both sexes black, .tiirciiiia Town. 



Mesonotum not so marked ; vertex mostly black ; anteiiiiie of male only with 



third joint yellow anibigiia var. nov. 



Micropeza tnrcaiia Town., Trans. Kans. Acad. Sci., xiii, 1.36, 1894. 



One % . HighroUs, New Mexico (Viereck and Rehn). This 

 specimen agrees so well with the typical description that there seems 

 to be no doubt about it being this species, but it shows a few char- 

 acters that differ from the typical, and which, with son)e additional 

 characters, I will note here: the brown side stripes of the posterior 

 portion of the front, and the vertex, noted in the typical descrip- 

 tion, are connected by other lines which divide that portion of the 

 head into yellow areas. The main stripes run from tlie upper cor- 

 ner of each eye over the vertex, passing just inside or including the 

 outer verticals, tlien passing on down the occiput, where tliev unite 

 with eacli other at the neck ; another pair leave the main pair about 

 opposite the ocellar tubercle, includes tlie inner verticals, and unites 



