AMERICAN DIPTERA. 345 



The tendency where the male is black, for the female to be 

 reddish is quite marked in this genus, and furnishes interesting 

 study, and in my own case, has led to the uniting of adustus 

 and combustus, and abbreviates and bicolor. 



SYNOPSIS OF SPECIES. 



1. Scutellar bristles normal in length 2. 



Scutellar bristles reduced to denticles abbreviatus. 



2. Abdomen black 3 . 



Abdomen reddish 4. 



3. Bristles of coxae white; femora with reddish stripe before.. dispar. 

 Bristles of coxae black; femora wholly black combustus. 



4. Venter black 5. 



Venter reddish 7 . 



5. Wings brown or blackish 6. 



Wings hyaline coquillettii. 



6. All the femora with large black vittae above dispar. 



All the femora without black vittae above; usually wholly reddish. 



combustus. 



7. Wings hyaline; fuscous along veins luteus. 



Wings entirely hyaline 8 . 



8. Dorsum of thorax densely grayish pruinose; length 10 mm. 



semiustus. 



Dorsum of thorax yellowish-gray pruinose with three brown stripes; 



length 1 3 mm hy alimi s. 



Saropogon abbrcviatus. 



Saropogon abbreviatus Johnson, Psyche, X, 113, 1903. 

 || Saropogon bicolor Johnson, Psyche, X, 113, 1903. 



cj 9- — Length 9-12 mm. — Distinguished from all species here in- 

 cluded by its rather short stout abdomen; the minute pustules bearing 

 very short hairs upon the dorsum of the thorax and abdomen, and by 

 denticles (about six) instead of long bristles upon the scutellar margin. 

 The male is black; the female, as far as known, has the abdomen 

 reddish. 



cf. — Wholly black; face, front, occiput and the upper portion of 

 the mesopleurae and the dorsum of the thorax silvery white pruinose, 

 the bloom of the dorsum, except on the humeri, lateral margins and 

 scutellum, very thin and showing a trace of a faint median darker 

 stripe; remainder of pleurae, except a brownish pruinose area above 

 the hind coxae, polished. Antennae wholly black; segment 3 seems a 

 little more slender than in combustus or dispar. Thoracic dorsum and 

 tergum of abdomen thickly covered with minute pustules bearing short 

 stiff hairs which give the entire body, when viewed from above, a 



TRANS. AM. ENT. SOC, XXXV. (44) AUGUST, 1909 



