BIRDS OF ICELAND 79 



necessary to give a detailed description. In summer 

 and autumn its dark 'grousy' body and white wings 

 will distinguish it on the wing from anything else. 

 In winter, of course, it turns white. It is well figured 

 in Dresser's Birds of Europe, and the curious autumn 

 dress (which has caused confusion with L. mutus) is 

 described and figured by Messrs. W. E. Clarke and 

 Backhouse in the Ibis of October 1885. 



As with grouse in Scotland, the Rock Ptarmif^an in 

 Iceland have a way of increasing in numbers during 

 successive seasons, up to a certain point, and then 

 suddenly becoming scarce. This has been explained 

 by the occasional cold late springs which occur every 

 now and then in Iceland ; but I liappened once to be 

 there in a year when the Ptarmigan had become scarce 

 suddenly (though the spring had not been a particularly 

 late or cold one), and from various dead birds I 

 examined, I came to the conclusion that the decima- 

 tion of the species was due to an epidemic similar to 

 our grouse disease. There was the same emaciation, 

 featherless legs and toes, and inflammation of the 

 viscera, with abundant entozoa. 



Rallus aquaticus, Linn. Water Eail. 



Native name : ' Keldu-svm ' (Swamp-swine ! ). There 

 are also some antique names mentioned by 

 Grondal, but not, as far as I know, now in use, 

 viz. ' Loekjakraka,' ' JarSsmuga,' etc. 



Resident, not very uncommon in the south-east, but 



