'ANIMAL LOCOMOTION 191 



fully furred. Most of the prehensile-tailed animals 

 curl their caudal appendages in a downwards 

 direction when holding on to an object, but, curi- 

 ously enough, the Demerara tree-porcupine does 

 just the opposite. 



So highly prehensile is the tail of some creatures 

 that they can actually suspend themselves from a 

 branch by that member alone. Mr. Germain, 

 describing the habits of one of the capuchin monkeys, 

 writes : — ' I have sometimes seen them at a height 

 of about one hundred and fifty feet from the ground 

 suspend themselves by the tail from a branch, 

 then balance themselves, with all four limbs stretched 

 out ; then, all of a sudden, let thculselves go, and 

 falling for a distance of some twenty or thirty feet, 

 seize hold of another bough by the tail. In such 

 falls the outstretched arms seem only ready in 

 case of accident, for there is never any question 

 of maladroitness.' Mr. Bates also gives a very 

 interesting account of the agility of these monkeys, 

 the writer stating that when a troop of capuchins 

 are journeying in the forest and the leader ' reaches 

 the outermost branch of an unusually high tree, 

 he springs forth into the air without a moment's 

 hesitation, and alights on the dome of yielding 

 foliage belonging to the neighbouring tree, maybe 

 fifty feet below, all the rest following his example.' 



It is somewhat curious that not aU mammals 

 have the same number of digits on their hands 

 and feet. The African colobus monkeys and the 

 American spider monkeys have no thumbs, or 

 else merely rudimentary stumps ; while other 



