62 OEIGIN OF LIFE IN AMERICA 



others are circumpolar but too migratory. Only the genus 

 Lagopus is of special interest, because it occurs in all the 

 regions and countries so far discussed. It includes the 

 American and Old World ptarmigans and the European 

 grouse, all of which are more or less permanently resident in 

 the countries they inhabit. 



The willow ptarmigan (Lagopus albus) breeds in th^ 

 barren-grounds and further south. It has a very wide range, 

 inhabiting northern Asia, northern Eussia, and northern 

 and central Scandinavia. It is not found in Greenland or 

 Newfoundland, being replaced there by the rock ptarmigan 

 (Lagopus rupestris). The latter also lives in Iceland, 

 western Asia, arctic America and Japan. The third American 

 species is the white-tailed ptarmigan (Lagopus leucurus) 

 which frequents the Rocky Mountain summits from Alaska 

 to New Mexico. It is sometimes called the " white or snow- 

 quail." Besides the willow ptarmigan, we have in Europe the 

 common ptarmigan (Lagopus mutus), the red grouse (Lagopus 

 scoticus) , peculiar to the British Islands, and Lagopus hyper- 

 boreus of Spitsbergen arid Franz Josef Land. Long ago I 

 ventured to express the opinion that the genus Lagopus was 

 of North American origin having thence spread to Europe 

 and Asia.* 



Dr. Stejnegert has since pointed out that, by an unfortunate 

 oversight, I had included Greenland in the range of the willow 

 ptarmigan instead of the rook ptarmigan. He also argued 

 that the willow ptarmigan of Scandinavia is more likely to 

 have originated from the British red grouse than, as I thought, 

 vice versa. Though I still believe that the genus had a 

 North American ancestry, I quite concur with Dr. Stejneger 

 in the view that the points he raised cannot be reconciled 

 with the conclusions I formerly arrived at. The subject is 

 certainly worthy of further careful study. At any rate, this 

 instance shows clearly the much greater difficulties we have 

 to contend with in tracing the geological history of birds 

 than that of mammals. 



As we proceed southward from the barren-grounds we first 



* Soharff, E. F., " History of European Fauna," p. 336. 

 t Stejneger, L., " ScharfE's European Fauna," p. 105. 



