THE ALPINE FAUNA. 335 



and leucurus of Western North America. In Asia we 

 then again find two kinds of Grouse, very closely 

 related, and by some indeed regarded as belonging 

 to the same species. These are L. rupestris and 

 L. mutus. Mr. Ogilvie-Grant tells us of the former 

 (p. 49), that it is merely a more northern rufous form 

 of L. mutus, and .that it goes through similar changes 

 of plumage. In summer the males are readily dis- 

 tinguishable, but in winter it is impossible to tell 

 one from the other. " L. rupestris taken as a whole," 

 says Mr. Ogilvie-Grant, "appears to us barely specifi- 

 cally distinct from L. mutus" L. rupestris occurs 

 not only in Northern Asia, but crosses the Behring 

 Straits to Arctic America, being still found on the 

 Aleutian Islands, which represent the last remains 

 of the former land-bridge between Asia and North 

 America, then eastward to Greenland and Iceland. 

 However, while this form does not cross the confines 

 of Asia in a westerly direction, its near relative 

 L. mutus better known as the Ptarmigan does; 

 and may perhaps have entered Europe as a Siberian 

 and also as an Arctic migrant It is still found in 

 the Ural Mountains, in Finland, and the highlands 

 of Scandinavia. It is gradually being driven out of 

 the Alpine lowlands, while it has long ago dis- 

 appeared from Germany, France, and Austria in 

 fact, from all the lowlands of Europe. It has also 

 been met with in the Pyrenees and in some of the 

 Spanish mountains. Similarly, the bird has become 

 extinct in England and Ireland, while it is becoming 



