2 INSECUTOR INSCITI.^ MENSTRUUS 



as at Winnipeg or Ottawa, with the Rocky Mountain species 

 added in the high elevations. The Nass, Stikine, Taku and 

 Alsek valleys, flowing into the Pacific, have not been explored ; 

 but they are all smaller than the Skeena, and probably do not 

 present different faunistic conditions. 



Fraser Valley. — From the junction of the Fraser and 

 Nechaco at Prince George, the Fraser Valley broadens out 

 southward, producing a flood-plain, in which many pools are 

 formed by seepage at the time of floods from the melting 

 snows of the mountains. A special fauna has adapted itself 

 to these conditions, although it is few in species. An economic 

 problem has arisen in the lower valley, involving this fauna, 

 which is being investigated by Mr. Eric Hearle under the 

 direction of Dr. C. Gordon Hewitt. A report may be ex- 

 pected later from these gentlemen, so I will not deal with the 

 fauna here. 



Skeena Valley. — The lower Skeena River forms flood-pools 

 in the same manner as the Fraser, but there is no broad flood- 

 plain and the whole region is forested. In these pools five 

 members of the Canadian fauna have established themselves 

 in the following order of abundance: lasarensis F, & Y., 

 cinereus Meig., intrudens Dyar, diantaeus H., D. & K., and 

 pionips Dyar, all normally early spring forms. None of the 

 river-pool species occur in these pools, nor any members of 

 the excrucians group, nor any other members of the spring 

 fauna such as punctor, decticus or pullatus, though these 

 species occur in early snow pools in the same region. Neither 

 do normally later-occurring species appear, such as canadensis 

 and vexans. Exactly what conditions this peculiar selection of 

 species in the Skeena flood-pools, I do not know. The com- 

 mon occurrence of diantaeus is the most interesting. I never 

 met this species commonly before, nor have I positive records 

 west of White River, Ontario. Early snow-pools also occur 

 in the Skeena Valley and these give rise to the ordinary Cana- 

 dian fauna, of which punctor is a very prominent if not domi- 

 nant member. 



