DISTRIBUTION AND TOPO GRAPHICAL ASPECT. 31 



trunks often beautifully pitted by the marks left on the 

 falling away of the fronds ; they grow to a height of from 

 twenty to fifty feet or more, from their tops sending out the 

 feathery fronds, often many feet in length, and yet so 

 delicate as to be put in motion by the gentlest breeze. On 

 some of the East Indian Islands the tree Ferns occur as 

 numerously as the crowded Firs in our plantations ; but 

 wherever they are found from the plains to an elevation of 

 3,000 to 4,000 feet the soil and atmosphere are full of 

 moisture. Yery noble arborescent Ferns are found in New 

 Zealand and Tasmania. 



The shrubby Ferns, those with short stems, surmounted 

 by tufted fronds, prevail rather at the tropics than at the 

 equatorial zone, and are found less frequently at the foot of 

 tropical mountains, than at an elevation of from 2,000 to 

 3,000 feet. Ferns of this aspect abound in the South Sea 

 Islands. Mr. Colenso describes one of the New Zealand 

 species as producing, from a main trunk twelve feet high, 

 fronds which form a droop often of eighteen feet ; such 

 plants, standing singly on the bank of a purling rill of 

 water, being objects of surpassing beauty. 



The herbaceous species are rather characteristic of the 

 temperate and colder zones : not that their number in 



