OF ANIMALS. 109 



When we compare with each other the different regions of the 

 globe, in respect to their zoological population, we are at first 

 struck by the extreme inequality remarked in the number of 

 species. In one country we find a great diversity in the form 

 and structure of the animals composing its fauna, while in another 

 place, there is great uniformity in this respect ; and it is easy to 

 perceive a certain relation existing between the different degrees 

 of zoological richness, and the more or less considerable -eleva- 

 tion of temperature. In fact, the number of species, both marine 

 and terrestrial, augments, in general, as we descend from the poles 

 towards the equator. The most remote lands of the polar regions 

 offer little to the observation of the traveller but some insects, 

 and in the glacial seas the fishes and mollusks are but little va- 

 ried ; in temperate climates the fauna becomes more numerous in 

 species ; but it is in tropical regions that nature has displayed the 

 greatest prodigality in this respect, and the zoologist cannot behold 

 without astonishment the endless diversity of animals that he there 

 finds assembled. 



It is also remarked that there is a singular coincidence between 

 the elevation of temperature in different zoological regions, and 

 the degree of organic perfection of the animals which inhabit 

 them. It is in the warmest climates that those animals live that 

 most nearly resemble man, and also those in the great zoological 

 divisions which possess the most complicated organization, and 

 the most developed faculties, while in the polar regions we meet 

 with creatures occupying a low rank in the zoological series. 

 Monkeys, for example, are confined to the warm parts of the two 

 continents ; the same is true of parrots among birds, of croco- 

 diles and tortoises among reptiles, and of land-crabs among crus- 

 ta'ceans, all of them the most perfect animals of their respective 

 classes. 



It is also in warm countries that we find animals the most 

 remarkable for the beauty of their colours, their size, and the 

 strangeness of their forms. 



Indeed there seems to exist a certain relation -between the cli- 

 mate and the tendency of nature to produce this or that animal 

 form. We observe a very great resemblance between most ani- 

 mals inhabiting the extreme northern and southern regions; the 

 fauna? of the temperate regions of Europe, Asia, and North 

 America, are very analogous in their general aspect, and in the 

 tropical regions of the two worlds similar forms predominate. It 

 is not identical species that we meet in distinct and nearly 

 isothermal regions, but species more or less approximating to 

 each other, which seem to be the representatives of one and the 

 same type. For example, the monkeys of India and of Central 

 Africa are represented in tropical America by other monkey'3 



