361 



decidedly traced than the longitudinal boundaries ; yet even m this 

 case the author states the lines of cessation to be determined more by 

 " the hilly and broken character of the surface " than by the degree 

 of latitude ; and instances the hills of Wales as bringing " several spe- 

 cies into a more southern latitude than it is at all likely they vs^ould 

 have been found in, if Wales and the adjacent English counties had 

 been as little diversified with high hills as are the counties under the 

 same latitude on the eastern side of the island." 



" The effect of the mountains, however, is prohably much more decidedly shown in 

 prolonging the southern range than in arresting the northern range of ferns ; since the 

 low coast-line, as weU as small plains and valleys around, or amongst the hills, may 

 still afford suitable localities for such ferns as are unfitted to bear the climate of the 

 mountain summits or acclivities, although capable of growing in the climate inciden- 

 tal to the latitude." — p. 98. 



The author's classification of ferns according to their range in Bri- 

 tain, and his observations, are very interesting. Those are first given 

 which " may be considered to have a range of latitude almost through 

 the whole of Britain." — 



Cistopteris fragilis Osmunda regalis Aspidium dilatatum 



Polypodium Phegopteris Scolopendrium vulgare Asplenium Filix-foemina 



vulgare Hymenophyllum Wilsoni Trichomanes 



Pteris aquilina Aspidium lobatum Ruta-mumria 



Blechnum boreale Oreopteris Adiantum-nigrum 



Botrychium Lunaria Filix-mas marinum 



Ophioglossum vulgatum spinulosum 



Four of the above twenty species " are very rare in the south of 

 England, namely, Botrychium Lunaria, Cistopteris fragilis, Hymeno- 

 phyllum Wilsoni and Polypodium Phegopteris, especially the last ; 

 and they are not found at all in the Channel Isles." Asplenium ma- 

 rinum, Scolopendrium vulgare, Ophioglossum vulgatum and Osmunda 

 regalis, are decidedly rare in the north of Scotland, " and they are not 

 found at all in the Faroe isles, though the Ophioglossum is stated to 

 grow in Iceland." 



The following are " boreal and mountain ferns, which are unknown 

 southward of the Thames." — 



Woodsia hyperborea Cistopteris dentata Asplenium septentrionale 



ilvensis Polypodium Dryopteris Aspidium Lonchitis 



Cistopteris alpina Asplenium viride Cryptogramma crispa 



Four species are given as being chiefly " confined to the middle la- 

 titudes of Britain." — 



2g 



