152 



genera especially are composed of a small number of aberrant 

 species {Chalcomyia aerea Loew, cyanea Smith, anomala, new 

 species, and depressa, new species, and Cynorhinella canadensis 

 Curran, hella Williston and longinasus Shannon) which do not 

 have a close uniformity among themselves and at the same time 

 act as intermediates between allied genera of both subfamilies. 

 According to our present understanding of the Chilosinae, this 

 group now being considered, Myiolepta, etc., comes within its 

 limits, chiefly due to the position of the discal cross-vein, i.e., 

 discal cross-vein rectangular and joining the discal cell before its 

 middle (usually oblique and joining the discal cell at or beyond 

 its middle in Xylotinae). 



Both Chalcomyia and Cynorhinella were established on a 

 single species each, which was of a rather extreme type, their pe- 

 culiar characters forming the basis of the descriptions. The new 

 species which have been added to them are not all as extreme in 

 these peculiar characteristics, hence the old characters do not suf- 

 fice to key them and it is necessary to redefine them. 



Myiolepta, sensu stricto, Chalcomyia and Cynorhinella are 

 separated from other Chilosine genera by : face black with or with- 

 out tubercle either in the male or in both sexes; body pile not de- 

 veloped scale-like; petiole beyond first posterior cell usually much 

 shorter than length of discal cross-vein. 



A^, Head not distinctly triangular, usually broadly elliptical; face tuberculate 

 in the male; third and fourth veins joining practically at wing margin; 

 second vein turned abruptly upward at tip Myiolepta. 



A^. Head distinctly triangular. 



Bi. Face not produced downward; tuberculate (as far as known) only in 



male of cyanea; a distinct petiole beyond first posterior cell, rarely as 



long as discal cross-vein; second vein distinctly curved at tip. 



Chalcomyia. 



B2. Face much produced downward; tuberculate in both sexes (as far as 



known); third and fourth veins joining practically at wing margin; 



second vein straight or slightly curved at tip Cynorhinella. 



The immature stages of Chalcomyia aerea are passed in rotting 

 logs. The other species probably have similar habits. 



Table of Species of Chalcomyia. 



Ai. Greenish bronze, clothed with short yellow pile; tibiae and tarsi largely yel- 

 low; scutellum subquadrate; male: face without tubercle; eyes well 

 separated, sides of front parallel on upper half. 

 Ri. Discal cross-vein joining discal cell much before its middle; posterior 

 cross-vein much less than the section of fourth vein above it. 

 Ci. Thorax flattened above; abdomen constricted basally ; hind femora 

 of male and female much swollen; male: face without tubercle; 

 eyes distinctly converging and rather closely approximated .... 



depressa, new species. 



C^. Thorax not flattened; abdomen broadened basally; hind femora 

 very slightly swollen; male: face with slight tubercle ; eyes slightly 



converging, well separated cyanea Smith. 



B2. Discal cross- vein joining discal cell nearly at its middle; posterior cross- 

 vein subequal to section of fourth vein above it . . anomala, new species. 



