AMERICAN DIPTERA. 323 



front legs are clothed above with appressed white pile, and 

 that the color of the wings is apparently variable. 



In 1904 I sent a rather poorly-preserved male specimen to 

 Mr. Coquillett, of which he wrote tinder date of March 16th, 

 "the specimen is not in the best condition for comparing or 

 studying, but it is apparently identical with my H. ludius. 

 The coloring of the wings appears to be variable in the same 

 species of this genus." This specimen had pure hyaline wings, 

 as senilis is described to have. There is a pair of Heteropogons 

 at the Brooklyn Institute from South Creek, Beaver Co., Utah, 

 named by Mr. Coquillett " senilis." Both the male and female 

 have the wings pure hyaline, but the male has all the front 

 tarsal segments, instead of the first, clothed above with ap- 

 pressed white pile. The specimen from Florida recorded by 

 Prof. C. W. Johnson as senilis (Proc. Acad. Nat. Sci. Phila., 

 1895, page 323) is, by comparison, the same as the specimen 

 named for me by Mr. Coquillett as ludius. If the amount of 

 pile on the front tarsi is variable in its extent, my key to the 

 males will be of little use. 



Heteropogou iiiaceriiius (PI. X, fig. 5.) 



Dasypogon macerinus Walker, List, II, 356, 1849. 

 Heteropogon gibbus Loew, Cent., VII, 58, 1866. 

 (^ 9 • — -Length 10-12 mm. — Black; head, thorax excepting the 

 stripes on dorsum and the posterior angles of the first four abdominal 

 segments whitish pruinose; wings hyaline, the costal margin and 

 apical half blackish. In the male the front metatarsi with dense 

 appressed white pile; the middle tibiae with a black brush. 



9- — Head covered with a whitish or pale yellow bloom; occiput 

 more obscurely covered with white pile and with white and black 

 bristles; pile of front white; bristles of ocellar tubercle black. First 

 two segments of the antennae reddish-brown with black pile, the second 

 segment beneath with a very long black bristle; third segment black, 

 longer than the first two basal segments taken together, tapering to 

 point; style very long, very slender, nearly as long as the basal seg- 

 ments taken together. Mystax white or very pale yellow, black on 

 the oral margin, very fine, extending upward to the antennae. Palpi 

 for the most part with black pile, occasionally with white and black 

 pile mixed; beard white. Thorax grayish pruinose, the three dorsal 

 stripes broad, black, very much abbreviated behind; the lateral stripes 

 brownish, subinterrupted; humeri and pleurae mostly reddish-brown. 

 In many specimens the whole thorax except the dorsal stripes, is red- 



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



