284 OBJECT OF THE AUTHOR. 



miuent features of the physiognomy of the Desert World, and not to 

 reproduce its more minute details. 



My embarrassment, then, arises less from the multitude and infinite 

 variety of the objects we have to examine, than from the difficulty of 

 harmonizing the study with the divisions of this work. How, in fact, 

 can I establish a positive distinction between the animals of the 

 Prairies or the Savannahs and those of the Forests, between those of 

 the latter and the animals proper to the Mountains ? For such 

 a purpose it is needful that each of these forms of the Desert 

 World should possess its peculiar fauna ; which is true only within 

 very narrow limits. In reality, most animals inhabit or frequent, 

 according to circumstances, sometimes one district, sometimes another, 

 without its being possible to assign with any amount of precision 

 their habitual, or simply their occasional, abode. 



I shall avail myself, therefore, of the liberty allowed to every 

 writer who does not design a purely didactical work, by not unneces- 

 sarily troubling myself whether the animals whose organization or 

 characteristics attract our notice, particularly affect a low or elevated 

 locality, the shady wood or open plain, the pestilential swamp or the 

 river-watered valley, and by permitting myself, except in the case of 

 some evident and constant partiality, to place them where the most 

 eminent observers assure us they are really, if not exclusively, met 

 with. 



On this account, the plains, more or less densely wooded and 

 broken up, which occupy the greater portion of the African Continent, 

 will readily furnish us with the opportunity of studying the majority 

 of animals indigenous to that continent, and, in general, to the entire 

 Tropical zone of the Old World. In fact, nearly all the genera of 

 Mammals, Birds, and Reptiles, are there represented by their most cha- 

 racteristic types. Clothed with a luxuriant vegetation ; watered by 

 periodical rains and numerous streams ; intersected by thick masses of 

 forests, groves, and thickets; relieved from monotonous uniformity by 

 mountain and ravine, by marshes and lakes of vast extent, these 

 fields ever exhibit that aspect of busy life under which we love to 



