STEJNEGER] ANIMALS AND PLANTS OF NORWAY 481 
in this case the two theories mutually support each other and thus, 
to some extent, possess the merit of corroborative evidence. 
There are two birds, however, the geographical distribution of 
which is so interesting and bears so directly upon the attempt made 
in this essay to demonstrate the existence of a well-assorted and 
peculiar biota having made its way from Scotland to west Norway 
since the climax of the glacial epoch, that their case deserves a 
closer scrutiny in this connection, especially as their geographical 
distribution has never been viewed from this standpoint before. It 
is somewhat parallel to that of the ptarmigan (Lagopus mutus), 
but as I have already referred to that species before in a similar 
connection (Amer. Natural., Xxxv, 1901, p. 106) and am going to 
allude to it again in a subsequent chapter of this paper (p. 488) I 
shall not mention it further here. 
The first of the two birds is the twite, or “mountain linnet”’ 
(Cannabina flavirostris). As a breeding bird it is absolutely con- 
fined to Ireland, northern Great Britain and western Norway. Pro- 
fessor Newton (Yarrell’s Hist. Brit. Birds, 4 ed., m1, 1876, p. 161) 
in speaking of the distribution of this bird in England says that “ it 
breeds in some abundance in the more hilly districts of the Midland 
Counties—Hereford, Salop, Stafford, Derby and Chester, as well 
as in North Wales and the Isle of Man, and on elevated moorlands 
in the higher glens with increasing frequency northward from 
Lancashire and the West Riding of Yorkshire to Shetland, though 
in some districts it is rather scarce, and its, stronghold in the west of 
Scotland is the Outer Hebrides. In Ireland it is found from north 
to south, and probably breeds in suitable localities throughout the 
island.” In Norway it breeds rather commonly along the west 
coast from Jederen northward to Lyngen (70° north latitude). 
Collett “ found it most numerous on the islands of Bergen Stift, and 
on the Trondhjemsfjord and on Hitteren.” Small colonies have 
also been found in the Alpine belt of the western mountains (Collett, 
Nyt Mag. Naturv., Xxxv, 1893, p. 83). 
The twite is not a regular migratory bird, but belongs to the 
category of winter birds which Seebohm aptly calls “ gipsy mi- 
grants.” It does not winter only in England, but in Norway as 
well, occasionally even as far north as Trondhjem, though many 
extend their irregular wanderings to the continent. 
Cannabina flavirostris although now more or less confined to 
the islands and coasts of the north Atlantic is not originally a mari- 
time bird, and it is very extraordinary indeed that we do not find it, 
or a representative of it, in the mountain districts of central and 
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