318 Professor Aldricli on the 



on the hind side below the middle with a row of small bristles. 

 Hind metatarsus thickened, half as long as the following joint. 

 Wings broad, yellowish ; first and second veins far from the costa, 

 fourth only gently curved, ending behind the apex, nearly parallel 

 to the third. Posterior cross-vein long, almost twice its length 

 from the border ; second posterior cell large. Anal angle well 

 developed. 



$ . Much smaller than male. First joint of antennae not 

 elongated. Arista scarcely thickened. Face moderately narrow, 

 parallel, the palpi and proboscis rather prominent, brownish. 

 Abdomen usually not compressed, the dorsum wholly brownish- 

 black ; venter yellowish. Fore pulvilli not enlarged. Hind tibiae 

 as in the male, but the bristles fewer and shorter. Wings a little 

 narrower. 



Length, male, 2'6 ; female, 1'7 mm. 



1000 to 1500 feet altitude. June. Numerous males 

 and females. 



POLYMEDON. 



Osten Sacken, Western Diptera, 317, 1877. 



This genus will have to be somewhat amended^ as it 

 should evidently include the following species. Baron 

 Osten Sacken, in establishing it, had only one species, 

 and consequently did not succeed in separating per- 

 fectly the generic and specific characters. The long cilia 

 of the tegulae, absence of acrostichal bristles, and large 

 swelling of the costa, are characters that pertain only to 

 the male of P. flabellifer, and are not generic. In the 

 species here described, the hind metatarsi are in the male 

 decidedly, in the female slightly, shorter than the follow- 

 ing joint. Mr. Samuel Henshaw, at my request, kindly 

 examined the types of P. flahellifer in the Museum of 

 Comparative Zoology, Cambridge, Mass., and informs me 

 that the hind metatarsi are not shorter than the following 

 joint. 



In the generic diagnosis, add " above '' to the clause, 

 " First joint of hind tarsi without bristles.'' 



1. Polymedon superbuSy n. sp. (PI. XI., fig. 103, head 



of $. PI. XII., fig. 113, wing; fig. 118, head of 



? ; fig. 119, head of 6.) 



$ . Head large and high. Face wide ; about half-way to the 



lower corner of the eye it is bent backward obliquely and grows 



