Diptera 65 c 



With the male are several females which I consider to be of this species. 

 The description is as follows : — 



Black, less distinctly shining than the male, the thorax very densely pruin- 

 escent, the centre with two narrow, pale grey vittse, and the lateral margins 

 broadly pale grey. Abdomen immaculate. Wings slightly greyish. Calyptrae 

 • white. Halteres yellow. 



Frons, at vertex, about two-fifths the head-width, slightly broadened 

 anteriorly, each orbit at middle about one-third as wide as interfrontalia, the 

 surface with many short hairs, four to six incurved bristles on lower portion 

 and two sUghtly outwardly-directed ones on upper portion; cheeks higher 

 than in male and with very few short hairs above the marginal bristles. Thorax 

 much less hairy than in the male, the prealar bristle absent. Abdomen pointed 

 at apex. Bristling of the tibiae very variable, fore pair with zero to three pos- 

 terior and zero to three postero-ventral bristles, and very rarely one antero- 

 dorsal; mid pair usually with one or more ventral, two to four antero-dorsal, 

 three to four postero-dorsal, and three to four postero-ventral bristles; hind 

 pair with from two to five bristles on antero-ventral, antero-dorsal and postero- 

 dorsal surfaces. 



Localities: one specimen with same data as male; one specimen same 

 locality as foregoing but with date of July 10, 1916; one specimen. Young point. 

 Northwest Territories, July 18, 1916; one specimen, cape Bathurst, Northwest 

 Territories, July 26, 1916; one specimen, west of Konganevik, Camden bay, 

 Alaska, July 4, 1914 (all F. Johansen). 



This species differs from any member of this genus known to me in the 

 structure and armature of the hind tibiee, the bare eyes, almost bare arista, and 

 black halteres. 



Limnophora Robineau-Desvoidy. 



There are two specimens in the collection referable to this genus, a male 

 and a female, neither of which it is possible to identify conclusively because 

 of the poor condition. The only species of the genus which I have previously 

 seen from the arctics of this continent is nobilis Stein. Neither of the specimens 

 before me belongs to that species, and apparently they differ specifically from 

 each other also. 



The immature stages of the genus are unknown. The flies are commonly 

 found close to water, being usually abundant on the shores of lakes and rivers, 

 and some of the most aberrant forms occur on the seashore. 



I have found one species in Scotland feeding upon insects, but whether it 

 killed the specimens itself or merely appropriated the discarded prey of other 

 predators I can not say as I did not see it catch any flies. The proposcis is 

 not adapted for piercing, though armed at apex with chitinous rods which may 

 serve to abrade the integument and so enable the insect to feed in a predatory 

 manner. 



Limnophora,. sp. 1. 



A male specimen taken at Cockburn point, Dolphin and Union strait. 

 Northwest Territories, September 7, 1914 (F. Johansen), has the eyes separated 

 by slightly more than the distance across posterior ocelli, the orbits narrower 

 than interfrontalia at its narrowest point; arista pubescent; thorax with three 

 strong pairs of postsutural dorso-centrals; presutural acrostichals irregularly 

 four-rowed; abdomen with large, subtriangular, separate, brown spots; fore 

 tibia with one posterior bristle; mid tibia absent; hind tibia with two antero- 

 dorsal, and two weak postero-dorsal bristles; third vein bare at base; veins three 

 and four divergent apically, last section of four about 2 • 5 as long as preceding 

 section; outer cross-vein straight. 



Length, 4-5 mm. 



Vol. iii— 46963— 5 



