184 
APES AND MONKEYS. 
full-grown. It measured 16 inches in length, exclusive of the tail; the whole 
body was covered with long and shining dingy-white hair, the whiskers and beard 
only being of a tawny hue. It was kept in a house, together with a coaita and a 
caiarara monkey (Gebus albifrons). Both these lively members of the monkey order 
seemed rather to court attention, but the howler slunk away when any one ap¬ 
proached it. When it first arrived, it occasionally made a gruff subdued howling 
THE BLACK HOWLER (-J ll.lt. size). 
noise early in the morning. The deep volume of sound in the voice of the howling 
monkeys, as is well known, is produced by a drum-shaped expansion of the larynx. 
It was curious to watch the animal while venting its hollow cavernous roar, and 
observe how small was the muscular exertion employed. When howlers are seen 
in the forest, there are generally three or four of them mounted on the topmost 
branches of a tree. It does not appear that their harrowing roar is emitted from 
sudden alarm; at least, it was not so in captive individuals. It is probable, how¬ 
ever, that the noise serves to intimidate their enemies.” 
