82 c Canadian Arctic Expedition, 1913-18 



HELOMYZID^:. 



The larvae of this family live in carrion and manure. Some of the species 

 are found in caves and in underground nests of rodents. 



The family is represented in this collection by imagines only. In order to 

 facilitate the indentification of the genera in this paper a generic synopsis is 

 given herewith. 



Key to Genera. 



1. Humeral bristle present 2 



Humeral bristle absent 3 



2. Thorax with five dorso-centrals Helomyza Loew. 



Thorax with two dorso-centrals Achaetomus G'oquillett. 



3. Thorax with one pair of dorso-centrals Porsenus Darlington. 



Thorax with at least two pairs of dorso-centrals 4 



4. Mid tibiae with long bristles on middle Oecothea Haliday. 



Mid tibia? without bristles except at apex 5 



5. Thorax with five or more pairs of dorso-centrals 6 



Thorax with two pairs of dorso-centrals Neoleria, gen. n. 



Thorax with three pairs of dorso-centrals TephrocMamys Loew. 



Thorax with four pairs of dorso-centrals 8 



6. Scutellum with six bristles; inner cross-vein much before end of first vein; mesopleura 



bare Anorostomoides Malloch. 



Scutellum with four bristles 7 



7. Inner cross-vein distinctly before end of first vein; frons in male very narrow; propleural 



and mesopleural bristles present t Heteromyza Fallen. 



Inner cross-vein at or beyond end of first vein; propleural and mesopleural bristles 



absent; eyes of male widely separated Allopfujla Loew. 



8. Eyes very small, not much larger than antennae; arista remarkably long; vibrissa? 



strong Eccoptomera Loew . 



Eyes much larger than antenna?; arista short; vibrissa? short and weak; face receding, 



oral margin not developed Anorostoma Loew. 



Eyes large; arista long; vibrissa? strong; mouth margin well developed Leria Loew. 



Oecothea Haliday. 



There is a large series of a species of this genus in the collection. I cannot 

 identify it with any of the previously described European species and it differs 

 essentially from fenestralis Fallen — a species occurring in Europe and North 

 America. 



Oecothea aristata, n. sp. 



Male and Female. — Head, anterior lateral angles of thorax, greater portion 

 of scutellum, hypopygium of male, genital segments of female, and the legs 

 reddish testaceous; upper portion of head and greater portion of occiput, thorax 

 abdomen, coxae, sometimes median portion of femora, and whole of tarsi fuscous. 

 Wings yellowish, cross-veins not infuscated. 



Frons about two-thirds the width of head, orbits with one bristle near 

 middle; interfrontalia with sparse, short hairs; antennae small, third joint barely 

 longer than second; arista very slender, nearly bare, about 2-5 as long as head, 

 with a very short swelling at base; face with a broad central carina which is 

 flattened and broadened below, covering the entire centre of face, cheeks with 

 one strong vibrissa and a number of short setulae; eye about equal in height 

 to cheek at posterior margin. Three pairs of postsuturals present; propleura 

 with one bristle; a few short setulae below anterior spiracle; mesopleura with 

 or without a short bristle; sternopleura with one long bristle and a number of 

 short setulae; pteropleura bare; hypopleura with a number of minute setulae 

 below spiracle; scutellum bare on disc, margin with four bristles. Abdomen 

 of male subcylmdrcal, fifth sternite with short, stubby setulae on apical half; 

 hypopygium large, knob-like; abdomen of female more flattened, genital 

 segments small. All femora of male slightly thickened, their antero- and postero- 

 ventral surfaces each with a series of short black bristles; femora of female not 



