87. FiLiCES. 257 



Whether its austral line can be drawn farther eastward 

 than the county of Oxford is very doubtful. P. Dryopteris 

 is stated by Warner, in Plantfe Woodfordienses, to grow 

 very sparingly on the walls of Chingford church in Essex; 

 but if either sj)ecies grows there, the probability would 

 seem to be greater for P. ealcareum. Taking England 

 alone, apart from Scotland, the distribution of the present 

 species is more boreal than austral ; and it might thus 

 almost as truly be assigned to the Scottish as to the 

 English type, although its total absence from Scotland 

 would appear to render that a misnomer, and indicate the 

 English type. It would associate with that small inter- 

 mediate and partially distributed group, mentioned under 

 Hutchinsia petrsea (Br. — mis-written Linn.) in vol. i. p. 

 120, of this work. Mr. Thomas Clark informs me that 

 the altitudes at which this species grows on Cheddar cliffs, 

 in Somerset, are about 250 and 800 feet. Its highest 

 limits in the northern provinces of England have yet to be 

 ascertained. 



1378. Allosorus crispus, Bernh. 



Area 1 * * * 5 6 7 8 9 10 11 12 13 14 15 16 17 18. 

 South limit in Somerset, Worcester, Derby. [Devon ?] 

 North limit in Hebrides, Sutherland. 

 Estimate of provinces 15. Estimate of counties 40. 

 Latitude 51 — 59. Highland type of distribution. 

 A. A. regions. Midagrarian — Superarctic zones. 

 Decends to 150 yards, in North Wales. 

 Ascends to 1150 yards, in West Highlands. 

 Range of mean annual temperature 46 — 35. 

 Native. Rupestral, Pascual. Frequent on the moun- 

 tains in many parts of Scotland and the northern provinces 

 VOL. in. 3 L 



