THE ARCTIC FAUNA. 143 



with the Siberian migrants from Central Asia, where 

 indeed the genus had its original home. The Black 

 Cock (Tetrao tetrix) and the Capercaillie (Tetrao 

 urogallus) have also come to us from the east, 

 and have even penetrated into Ireland. They are 

 therefore some of the few instances of members 

 of the Siberian invasion having become temporarily 

 established there. 



Reptiles and amphibia are altogether unknown in 

 the Polar Regions, but a large number of fish, chiefly 

 marine, have taken their origin there. The Salmon 

 family are of Arctic origin, as also are the Stickle- 

 backs and the Perches, many of the Cod family, the 

 Herrings, and several of the Flat fish. 



It would lead me too far to refer to the invertebrate 

 fauna of the Polar Regions, but a few remarks on the 

 Arctic plants may not be out of place. 



The principal Arctic genera are Satix, Ranunculus, 

 Draba, Pedicularis, Potentilla, Saxifraga, Carex, 

 Juncus, Luzula, Eriophorum, and others. 



Among the most characteristic Arctic plants may 

 be mentioned Dry as octopetala, to which I have already 

 referred as occurring in the west of Ireland; Saxifraga 

 oppositifolia, another British species, occurs in the 

 higher mountains of Scotland, Ireland, and Wales; 

 Braya alpina, Papaver nudicaule. Lychnis apetala, 

 Diapensia lapponica, and Lobelia Dortmanna, which is 

 found in the lakes of Scotland and Ireland. The 

 dwarf birch (Betula nand) also, which still occurs 

 in Scotland and the North of England, and which 



