MOSSES IN EUROPE, AND THEIR ASPECTS IN NATURE. 31 



mountain range, the Dovrefjeld, are rich in mosses, being exposed 

 to the influence of the Gulf-stream, which greatly modifies the 

 severity of the climate. Besides this superficial distribution^ an- 

 other still more important is that in altitude, or range above the sea 

 level, and this is marked out by lines gradually descending as we 

 pass from south to north, until in the Arctic Zone they become 

 closely approximated ; in fact, the lines form arches from pole to 

 pole, whose highest point or crown is over the equator. 



Prof. Schimper indicates five regions for the distribution of 

 mosses altitudinally, all of which are characterised by certain pre- 

 dominant species, just as they are by certain flowering plants, and 

 we have only to climb any elevated mountain range to find that the 

 plants we first met with disappear as we ascend, and are replaced by 

 other species, which also have their limits, until we reach the line 

 of perpetual snow, beyond which all is solitude and desolation, and 

 the crustaceous lichens even fail to maintain a footing. 



Commencing at the sea level we have : 



1st. — The Campestral Region, or that of the cereal plants and 

 fruit trees, which extends up the mountains to a variable height, 

 according to the latitude ; thus in the Southern Zone, on the 

 Pyrenees, it reaches to 3100ft. on the south side and 2100ft. on 

 the north ; in the Middle Zone it approaches 1400 in the southern 

 parts, falling to 750 and 500 at its northern limit ; in the Northern 

 Zone it descends so rapidly from 500 to that at 66° it disappears, 

 and thus in the Arctic part of this zone the campestral region is 

 altogether wanting. 



You will observe that this region in the separate zones presents 

 very different conditions of surface : we have the artificial sub- 

 stratum of cultivated fields and roadsides, hills and woods, open 

 desert plains, heaths, bogs, and marshes, and all varying inter se, 

 according to the nature of the soil, whether calcareous or argilla- 

 ceous, sandy, rocky, or stony ; and according to this difference in 

 the chemical constituents of the soil are certain species predomi- 

 nant, and hence the aspects of the campestral region are in the 

 highest degree varied. Many mosses of this region extend upward 

 to the one above, from which again others descend into it. It would be 

 tedious to enumerate the species occurring in this region, since 

 they comprise all that are generally diffused over our downs and 

 heaths, woodland banks, and hills of moderate elevation. 



2nd. — The Montane Region ascends from the cultivated region to 



d 2 



