1911] 



Swarth: Alaska Expedition of 1909. 



155 



are from these adjacent islands. They have one species of 

 mammal {Microtus coronarius) common to the two, and as far 

 as known occurring nowhere else; and one other species 

 {Peromyscus sitkensis) found on both which is not found on 

 either of the large islands closest to them. The sooty grouse 



DISTRIBUTION 

 Dendragapus o. fu/iginosus 



SOUTHEASTERN ALASKA 



Fig. 2. — Map showing the range of the sooty grouse {Dendragapus 

 oiscurus fuliginosus) in southeastern Alaska. It occurs on some of the 

 more remote western islands of the archipelago, but is absent from others 

 lying nearer the mainland. 



{Dendragapus) is found on Coronation Island, but is absent from 

 Warren where apparently the spruce grouse (Canachites) occurs. 

 What the obstacle may be that stops a strong flying bird, and 

 yet permits the passage of small and feeble terrestrial mammals 

 it is hard to imagine. It is of interest to note in this connection 



