DIPTERA. 



33- 



DOLICHOPODIMJ * (p. 213). 



DOLICHOPUS (p. 213). 

 3. Dolichopus bifractus. 



Dolichopus bifractus, Loew, Mon. N. Am. Dipt. ii. p. 53 \ 



Bab. North America, United States K— Mexico, Cuernavaca (H. II. Smith). 



One female of this widely-spread and common N.-American species was found at 

 Cuernavaca by Mr. Smith. The third joint of the antennae is almost black, a 

 peculiarity I have not noticed in any other specimen, though it is often a little 

 infuscated. 



Dolichopus myosota (p. 213). 



To the locality given, add :— North America, Idaho. 



This species was described from specimens from Northern Sonora. It is common in 

 the foot-hills of the Eocky Mountains in North Idaho, and probably occurs all through 

 the intervening country. I have not seen a Mexican example. 



POLYMEDON. 



Polymedon, Osten Sacken, Western Diptera, p. 317 (1877) ; Aldrich, Trans. Ent. Soc. Lond. 1896 ; 

 p. 318. 

 This genus is nearly related to Tachytrechus, but differs in the more uniform course 

 of the last section of the fourth vein, and more especially in the structure of the face 

 of the male, which extends like a silver ribbon below the level of the eyes. Three 

 new species are represented in the present collection, and two were described in 

 the above-cited papers. They fall into two series: one, including P. argentatus, 

 P. triangularis, and P. superbus, not differing in a striking manner from Tachytrechus ; 

 the other, including P. flabellifer and P. nimius, characterized, additionally, by an 

 enormous development of the tegular cilia and the first section of the costa in the 



male sex. 



Table of the Species knoivn to me f . 



1. Femora black ~- 



Femora yellow 3- 



2. Antennce reddish on the underside [flabellifer, 0. S.J 



Antennas wholly black argentatus, sp. n. 



* By Prof. J. M. Aldrich, of the University of Idaho. 



t In addition to the above-mentioned species, another, P. castus, has lately been described by Wheeler in 

 the ' Proceedings of the California Academy of Sciences ' [3rd ser. vol. ii. p. 6 (1901)]. It is based on a single 

 female from Arizona, and appears to be closely related to P. nimius, from which it differs in having the 

 third joint of the antenna wholly black, which will readily distinguish the two species. 



MtC f'T: 



' 



