THE CANADIAN ENTOMOLOGIST 101 



THREE DIPTERA FROM THE MIOCENE OF COLORADO. 



BY T. D. A. COCKERELL, UNIVERSITY OF COLORADO, BOULDER. 



Atrichops hesperius, n. sp. (Leptidae). 

 Length 6 mm., wing 5 mm.; robust, of the usual form: tarsi 

 microscopically hairy, not at all bristly or spiny; wings clear or 

 almost, the venation as preserved pale reddish. Venation as in 

 Atrichops crassipes (Meigen), except as follows: Auxiliary vein 

 reaching costa distinctly before middle of wing; end of subcostal 

 cell larger; base of second posterior cell more oblique; anal cell not 

 so broad. The anal cell is closed a short distance before the wing- 

 margin. The long second submarginal cell has its lower side 

 measuring about 2560 microns. The anterior cross-vein is about 

 290 microns from basal corner of discal cell. Florissant; Station 

 B 13 (S. A. Rohiver). 



The shape of the wings and the details of the venation place 

 this species in Atrichops Verrall, rather than in Atherix. Atrichops 

 has hitherto contained a single living Palaearctic species, so it is 

 interesting to find it in the Miocene of America. It is less pubescent 

 than Atherix (and in this the fossil also agrees) and the venation is 

 on the whole less specialized. 



Xylomyia moratula, n. sp. (Leptidae). 



Length 6 mm., wing about 53^; of the usual form; head and 

 thorax black, abdomen light reddish; legs reddish brown; tibiae and 

 tarsi not at all spinose or bristly; wings hyaline; venation as 

 preserved light reddish. Venation like that of X. maculata (Meigen) 

 with the same wide open second submarginal cell and arched upper 

 side of second posterior cell, though the latter feature is not quite 

 so extreme as in X. maculata. The anterior cross-vein is near to 

 the base of the discal cell as in X. maculata; the closer fourth pos- 

 terior cell is relatively narrow apically as in X. marginata (Meigen), 

 but its side on the third posterior, though long, is shorter than its 

 side on the discal cell, the reverse being true of marginata. The 

 insect is therefore entirely of the type of X. maculata, as opposed to 

 that of X. marginata, which is perhaps hardly congeneric. 



The following wing measurements are in microns: Length of 

 lower side of second submarginal cell about 1695; base of second 

 submarginal to anterior cross-vein about 1570; level of end of upper 



March, 1914 



