INSECUTOR INSCITI^ MENSTRUUS 81 



nigromaculis, the dominant prairie form, was taken at Belton, 

 well in the forested area ; but in general this statement holds 

 true. Further east on the plains mosquitoes appeared, in places 

 in great abundance, following unusually heavy rains. It ap- 

 pears, therefore, that this is a permanent condition, and not 

 due to temporary dryness of the region adjoining the mountains, 

 for this area was not unduly dry. 



Of the species comprising the Canadian fauna, only one, 

 Aedes punctor Kirby, is absent. This absence is worthy of 

 note, for punctor is one of the dominant and characteristic 

 species of the fauna proper. However, in the Rocky Mountain 

 region it appears to have dropped out completely. Certain large 

 individuals of lasarensis with fused mesonotal bands raised a 

 doubt at times, but there was nothing among the many hun- 

 dreds of specimens taken that could be positively identified as 

 punctor. The dominant species of the black-legged group is 

 lasarensis. It occurs everywhere in forest, abundantly on the 

 west of the divide, and east also, following down the river 

 valleys as far as there are any trees. The variation in colora- 

 tion is, as usual, considerable; but what makes identification a 

 trial to the nerves is the occurrence of natural hybridization. 

 Many of the specimens looked to me like hybrids when cap- 

 tured ; but it was only on careful examination that the fact 

 became apparent with the mounting of two hybrid males, 

 intrudens x lasarensis. These hybrids had an abnormal ap- 

 pearance, but from the coloration before mounting, I took 

 them to be a cross between cataphylla and pullatus. Neither 

 of these species, however, proved to be involved. These hybrids 

 occurred in the greatest abundance in the deep forest far from 

 habitation. At Belton. on the railroad, the phenomenon was 

 not noted, nor at the town of Whitefish, where large areas of 

 the forest have been cut over. But by the kindness of the 

 Superintendent of the Park, Mr. J. Ross Eakin, we were 

 enabled to visit a remote locality, some twelve miles to the 

 northwest of Lake McDonald. Here more hybrids were en- 

 countered than at any other place. Some also were taken to the 

 east of the divide, the males in question within a few miles of 



