87. FILICES. 253 



of the Bleclinum might be mistaken for (or only acciden- 

 tally substituted for) the Polypodium by a young botanist ; 

 but as Edmondston mcluded P. vulgare in his Shetland 

 Flora, published some years later, indicating it as " fre- 

 quent " in the Isles, it probablj^ enough does occur there. 

 Shetland is an intermediate habitat between Orlvney (Miss 

 Boswell, el'c), and Faroe (Sir W. C. Trevelyan), for each of 

 which there is sufficient authority. Probably scarce above 

 the agrarian region ; yet it may rise to a greater elevation 

 than 700 yards. 



1374*. Polypodium alpestre, Koch. 



(Pseudathyrium alpestre, Newm.) 



Area ^-****4(f^j(j.***^**15 16. 



South limit in Forfarshire. 



North limit in West Inverness-shire. 



Estimate of provinces 2. Estimate of counties 4. 



Latitude 50 — 57. Highland type of distribution. 



Arctic region. Midarctic — Superarctic zones. 



Descends to 800 yards, less or more. 



Ascends to 1000 yards, more or less. 



Range of mean annual temperature, say 39 — 36. 



Native. Rupestral. In July, 1841, I gathered two 

 fronds of this fern in the great corrie of Ben Aulder, a 

 lofty mountain situate on the west side of Loch Erricht, 

 Inverness-shii-e, wliich is part of the boundary line be- 

 tween the East and West Highland provinces. Another 

 frond of the same species was picked at some other spot 

 in the neighbourhood of Loch Erricht, probably on the 

 hills between Ben Aulder and the north end of the lake, 

 but it might be on the hills of Drumochter Forest, east- 

 ward of the lake ; and if the latter, the station would be 



