SECTION XIV 



DISTRIBUTION 



In discussing the various groups of animals, the subject of their 

 geographical aud geological distribution has in every case been 

 referred to, and the reader will already have noticed how strikingly 

 the different parts of the earth's surface at the present day, and 

 the different periods of its geological history, differ from one an- 

 other in respect of their animal inhabitants. In order to bring 

 forward the facts of distribution more prominently, the present 

 section will be devoted to this important subject. 



1. Geographical Distribution 



The facts and ideas of which the subject of Geographical Dis- 

 tribution takes cognisance are clearly brought out by comparing 

 the fauna of Great Britain with that of the most distant of her 

 colonies, New Zealand, including, in each case, the adjacent 

 islands. The two countries are not widely different in size. The 

 climate of each is temperate, Great Britain extending from about 

 50° to 60^ north latitude, and having a mean annual temperature 

 of about 48° F., New Zealand extending from about 84° to 48° 

 south latitude, and having a mean annual temperature of 55°. 

 Both contain mountainous regions, forests and arable land. The 

 climate of both is humid, the rainfall of Great Britain being from 

 about 25 to 30 inches in flat, 40 to 80 inches or more in mountainous 

 districts, while the average rainfall for the whole of New Zealand 

 is about 50 to 55 inches. The physical conditions of the two 

 countries are thus very similar, the chief differences being the far 

 higher summer temperature of the northern part of New Zealand, 

 and the far lower winter temperature of the northern part of 

 Great Britain. 



But when we come to compare the fauna? of the two countries 

 these similarities disappear. In Great Britain there are about 



