130 FAUNAS OF TROPICAL COUNTRIES. [CH. Ill 



flying moths of the tropics of the old and the new worlds, 

 the Agaristidse and Castniidse, the toucans of America 

 and the hornbills of the East also contribute to giving 

 them a similarity. So too the apes and monkeys ; while 

 the newts of the colder regions distinguish them from the 

 tropics. The humming-birds of America have a superficial 

 likeness to the sunbirds of the old world ; the tapir occurs 

 in tropical America and recurs in tropical Asia. Plenty 

 of other such resemblances might be cited. 



But a closer examination of the facts dispels the ideas 

 of a similarity of the fauna to which they at first give 

 rise. The humming-birds are not nearly related to the 

 sunbirds; nor are the toucans the nearest allies of the 

 hornbills; ornithologists think that the latter come next 

 to the hoopoes. The apparent similarity in fact is due 

 to a variety of causes. ' The deserts of America are 

 tenanted by sandy-coloured reptiles just as are the deserts 

 of Asia and Africa ; but in all cases it is believed that the 

 similar plan of coloration is not due to any affinity but 

 to their similar needs. The African lizard assimilates in 

 colour to the sand in and upon which it lives just as does 

 its American representative. Perhaps, as has been sug- 

 gested by a competent observer of the birds and beasts of 

 India 1 , the huge beak of the hornbill has been produced 

 in order to assist it in wrenching off from the stem the 

 often tough fruits upon which it feeds; the toucan may 

 have got its almost equally large bill by reason of the 

 same need. Forest country is inhabited by animals that 

 are adapted to life among trees, whence superficial simi- 

 1 A Naturalist on the Prowl, by " Eha." 



