rv. PHYSICAL GEOGRAPHY. 135 



S. Britain includes prov. 1 — 7 ; subprov. 1 — 18. 



M.Britain 8—14; 19—28. 



N.Britain 15—18; 29—38. 



A glance over the map in volume third will show these 

 divisions better than verbal explanations ; particularly 

 so, if possessors of the volume will trace two lines of 

 colour transversely along the two dividing boundaries. 

 Each of the divisions may be said to extend across about 

 three degrees of latitude, with the outlying addition of 

 Shetland to the most northerly one ; also some consider- 

 able irregularities with reference to the mathematical 

 lines of latitude, through the wavy course of the lines 

 which divide the provinces or counties, and in accordance 

 with which these divisions are made. Each of the divi- 

 sions has also its mountain ranges ; an important condi- 

 tion towards the data for anj'^ true or equal comparisons 

 between their respective floras. 



South Britain has the widest area of low and open 

 country, and relatively and absolutely the smallest extent 

 of mountainous ground. The hills of Mid Britain are 

 somewhat less elevated than are those of South Britain ; 

 three of the highest summits in Wales exceeding those of 

 the Lake district in North England, where the highest 

 hills of Mid Britain are found. The area of low and un- 

 dulating plains, at all corresponding with the downs and 

 intervening country of South-east England, is much less 

 in Mid Britain ; so that, viewed in the whole, the latter 

 has more of the mountainous character than South 

 Britain. In turn. North Britain is far more mountainous 

 than the other two divisions ; much exceeding them by 

 the vertical elevation of its hills, as well as by theii- bulk 

 and horizontal extent. The flora of North Britain is 

 consequently more alpine or arctic than the floras of the 

 other two more southerly divisions ; the influeiice of the 



