62 
ORIGIN 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 the 
barren-grounds and further south. It has a very wide range, 
inhabiting northern Asia, northern Russia, 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. Stejnegerf has since pointed out that, by an unfortunate 
oversight, I had included Greenland in the range of the willow 
ptarmigan instead of the rock 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 
* Scharff, R. F., “ History of European Fauna,” p. 336. 
t Stejneger, L., “ Scharfi’s European Fauna,” p. 105. 
