INSECUTOR INSClTliE MENSTRUUS 15 



the basal lobe is low-rounded, openly tubercular, with fine 

 setae, smaller and less developed than in mercurator. 



Aedes fitchii Felt. 



Male demonstrated from Dawson, Yukon Territory. Also 

 from Saskatoon, Saskatchewan, June 7, 18, 1918 (A. E. 

 Cameron), and Prince Albert, Saskatchewan, June 10, 1918 

 (A. E. Cameron), from Doctor Hewitt's collection. 



Larvae were obtained at Dawson. Head hairs, upper in 

 threes, lower double or single. Comb scales of the eighth seg- 

 ment long and thorn-like with small lateral fringes. Tracheal 

 tubes decidedly broad within the air-tube and not conspic- 

 uously angled in the eighth segment. Air tube shorter and 

 stouter than usual. 



These differ from Massachusetts specimens in the shorter 

 tube with broader tracheae, less strongly angled in the eighth 

 segment, the strong median spine on the comb-scales and the 

 less numerous head-hairs, which are, upper 3 or 4, lower 2 

 or 3 in typical fitchii. But they agree entirely in all these re- 

 spects with fitchii larvae which I obtained at Edmonton, Alberta. 



The male genitalia show a slight progressive difference west- 

 ward. In eastern specimens the filament of the harpago is 

 shorter proportionately to the stem. Plattsburgh, New York, 

 White River and Dryden, Ontario, Winnipeg and Aweme, 

 Manitoba, are about alike. The lengthening of the filament 

 appears gradually. Elkhorn, Manitoba, Oxbow and Prince 

 Albert, Saskatchewan, appear intermediate, while Regina and 

 Saskatoon, Saskatchewan, and Banff, Alberta, appear about 

 like Dawson, Yukon Territory. 



A western race of fitchii is thus indicated, but it would seem 

 to appear so gradually that probably there is no sharp demar- 

 cation. 



No varietal name is available, but it seems hardly worth 

 while to propose one deliberately. 



Total, 1,327 specimens, including excrucians, stimulans, 

 fitchii and mercurator , most of the captured adults not being 

 certainly separable: Edmonton, Alberta, May 11-20, 22, 25, 



