SPIDER MONKEYS. HOWLERS. 171 



than of walkers. They tread on the inner edge of the fore-paws, 

 and on the outer edge of the hind-paws; and endeavour to 

 assist themselves by attaching the tail to any object as they pro- 

 ceed. They often assume the erect attitude, however ; and then 

 use the tail as a means of balancing themselves. The proper 

 place for these monkeys, however, is among the branches of the 

 forest ; their movements are there rapid, easy, and unconstrained ; 

 and they swing from branch to branch, by means of their spider- 

 like limbs and their prehensile tails, with the greatest agility. 

 The tail is not only an instrument of prehension, but an organ 

 of touch ; the end of it is destitute of hair, and furnished with a 

 sensitive skin ; and it is capable of seizing small objects with great 

 address. These animals are said to introduce the extremity of 

 the tail, as a feeler, into the fissures and hollows of trees, for the 

 purpose of hooking out eggs or other substances. In the great 

 length of their arms, these Monkeys evidently represent the 

 Gibbons ; and they correspond with them also in temper, being 

 timid, gentle, and contemplative, with more intelligence than 

 most other Monkeys, and displaying agility only when roused. 

 The Mycetes, or Howling Monkeys, are distinguished from the 

 last, by their greater robustness, and by the diminished length 

 of their limbs ; by the presence of a thumb, which is, however, 

 not opposable ; and by the dilatation of the os hyoides ( ANIM. 

 PHYSIOL. 684) into a hollow drum, which communicates with 

 the larynx, and gives great additional resonance to the voice. 

 The howlings uttered by the troops of these Monkeys are de- 

 scribed by travellers as astounding. They are usually sent forth 

 early in the morning, at sunset, and during the darkness at 

 night ; but they are also heard when the overclouded sky 

 threatens an approaching storm. In their dispositions the 

 Howlers are melancholy and morose ; their movements are 

 tardy and inert, and, when on the ground, they never attempt to 

 walk on the hinder limbs alone. They feed principally upon 

 fruits and leaves. In the genus Cebus, comprehending the 

 Monkeys known as Sapajous, Sajous, and Capucins, the tail is 

 covered with fur to its extremity ; so that, although it is still 

 prehensile, it is not so delicate an organ of touch as in the pre- 



