A SnUI/x'R/.LS NEST. 93 



stupid inarsupials. ilic opossum lias a true tlunnb to his 

 liitul foot, which he uses hkc a liaiui, liesides pcxsso.ssitvjj 

 a very flexible tail ; atui the opossum is not onl)- pK - 

 verbiall)- cunning", but he also has alone succeedetl in 

 holdiii;^^ his own amonj; the hij^dily developed mammals of 

 America, while all the rest of his kind are now confined 

 to Australia, their compeers elsewhere having been killed 

 out without exception durin;^ the tertiary period b\- the 

 fierce competition of the lari^er continents. Wherever 

 we find a clever animal, like the doi;', without an)' j^rasp- 

 inc^ power, we also find a lar<;c development of the sense 

 of smell, which ma)- be regarded as to some extent com- 

 pensatory. lUit it must never be for^^otten that the 

 cleverness of the dog has been greatl)- increased by long 

 hereditar)' intercourse with man, wiiile tlie cleverness of 

 the elephant, the monke)-, and the opossum is all native 

 and self-evolved. The squirrel's paws stand him in 

 almost equal 1)- good stead. For though he has no 

 opposable thumb, he can hold a nut or a fruit between 

 them, rolling it about or atljusting it meanwliile : and 

 his teeth also serve as regular tools, which further enable 

 him to manipulate an object held in iiis paws almost as 

 well as an)' other animal except the apes and monkeys. 

 It is observable, too, that his tail belongs markedly to 

 one of the two t)-pes common among forestine tree- 

 haunting creatures. Those which crawl or hang among 

 the boughs have gctierally prehensile tails to aid them 

 in grasping the branches: those which run and leap from 

 tree to tree have generally bushy tails to aid them in 

 balancing themselves, and to act as a sort of aerial 

 rudder. In the fl)'ing squirrels and many other similar 

 exotic types the use of such tails as a parachute is su})i)le- 



