MUSEUM BULLETIN NO. 7. 



Mackenzie; Mackenzie river: 1 specimen. 

 Yukon Territory, Teslin lake: 4 specimens. 



It will be seen that the most southern birds are the largest 

 and lightest ; the northern smallest and darkest, while those from 

 lower British Columbia are intermediate though closer to the 

 southern than the northern race. The Mackenzie form, being 

 represented by only a single specimen in not very high plumage, 

 cannot be definitely placed in the series though it agrees closely 

 with the Montana and Idaho specimens. No specimens from the 

 type locality of richardsoni (the northeast corner of Rocky 

 Mountain park, lat. 53, long. 115) being obtainable I assume 

 from the above that it ranges up the east side of the Rocky 

 mountains and through them south of the International border 

 in unmodified form, while the intermountain birds, flemingi, as 

 they distribute northward from the boundary, become smaller 

 and darker. It is possible that on examination, birds from 

 farther north of Teslin lake will exhibit these characters in a 

 still more marked degree 



