87. FILICES. 255 



north of Scotland. It is the great rarity of the plant in 

 the most southerly or south-easterly provinces of Eng- 

 land, that suggests the boreal rather than the British type. 

 Of the 22 counties included in the four first provinces, 4 

 only have been reported to produce this species ; and one 

 of these (Middlesex) being little probable, and not certi- 

 fied on sufiicient authority, can scarcely be reckoned in 

 the census. Most of the other 60 counties doubtless 

 produce this fern, which has been actually reported from 

 about 45 of them. I do not know how far south this 

 should be deemed a plant of the coast level. The altitude 

 of its stations in the Channel and Peninsula may not be 

 quite so low as to warrant an indication of the coast level 

 in those provinces. The term ' rui^estral ' does not very 

 acciu'ately characterize the natural situations for this 

 species ; a combination of ' rupestral ' with ' sylvestral ' 

 and ' uliginal ' would be nearer the actual conditions of 

 its gi'owth, — a combination of drainage with shade and 

 humidity. 



1376. PoLYPODroM Detopteris, Linn. 



Area [1 3 3] * 5 6 7 8 9 10 11 12 13 14 15 16 17. 

 South limit in Glamorgan, "Warwick, Lincohi ? 

 North limit in Sutherland. 



Estunate of provinces 13. Estimate of counties 60. 

 Latitude 51 — 59. Scottish tj^pe of distribution. 

 A. A. regions. Inferagrarian — Superarctic zones. 



Descends to the coast level, in ? 



Ascends to 900 yards, in West Highlands. 

 Range of mean annual temperature 48 — 37. 

 Native. Rupestral, Sylvestral. The remarks on the 

 distributive t}^e of the preceding species, P. Phegopteris, 



