AMERICAN DIPTERA. 285 



Cyrtopogon tibialis. 



Cyrtopogon tibialis Coq., Proc. Ent. Soc. Wash., VI, 183, 1904. 

 " 9. — Length 9.5-11 mm. — -Near plausor, but the mystax is black 

 and rather sparse, not concealing the ground color, scutellum flat, etc. 

 Black; the halteres yellow; the tibiae, bases of tarsi and extreme 

 apices of femora reddish-yellow. Hairs of front and on upper edge of 

 occiput black, on remainder of occiput white; third joint of antennas 

 slightly longer than the first two joints taken together, greatly widening 

 medially, two and one-third times as long as the rather slender arista; 

 face strongly gibbous. Mesonotum gray pruinose, marked with a pair 

 of submedian brown stripes not extending on the posterior portion, 

 and on either side with a pair of large brown spots separated by the 

 suture; hairs sparse and rather short; bristles black; mesopleura and 

 sternopleura hairy; pteropleura bare; hairs of hypopleura whitish; 

 scutellum gray pruinose on the upper surface, sparsely covered with 

 long black hairs most abundant around the margin, devoid of stout 

 bristles. Abdomen polished, with a bluish tinge on the first five seg- 

 ments, a gray pruinose fascia on hind part of the first six segments, 

 that on the first and sixth broadly interrupted in the middle. Hairs 

 of coxae and femora white, bristles of tibiae and tarsi black, tarsal claws 

 whitish, their apical third black. Wings hyaline, small cross- vein near 

 one-third length of discal cell." 



Type.— U. S. N. M., Cat. No. 7957. Three female spec- 

 imens. 



Habitat. — Arizona (H. K. Morrison). 



Cyrtopogon rattus. 



Cyrtopogon rattus Osten Sacken, West. Dipt., 308, 1877. 



% 9 • — Length 9-10 mm. — Altogether covered with a yellowish-gray 

 bloom; thorax with a geminate black line in the middle; abdominal 

 segments on each side anteriorly with a polished black spot. 



Face and front grayish pruinose, the former with a white mystax: 

 the bristles above the mouth are black; ocellar tubercle and occiput 

 beset with whitish hairs; a small tuft of black hairs on each side of 

 the vertex near the upper corner of the eye. Thorax gray, with a 

 black double line in the middle, abbreviated before reaching the 

 scutellum; the lateral stripes are paler brown, ill defined and crossed 

 transversely by the grayish pruinose thoracic suture. The pile on 

 the thorax is whitish anteriorlv, black posteriorly; bristles black. 

 Scutellum gray, clothed with long, soft, whitish pile. The fan-like 

 fringe of hairs in front of the halteres is white. Abdomen gray, 

 clothed with soft, whitish pile; segments 2-6 on each side at the base 

 with a large polished black spot, diminishing in size on each subse- 

 quent segment. In the female these spots are much smaller. The 



TRANS. AM. ENT. SOC, XXXV. JULY, 1909 



