Howling Monkeys. 223 



than the boa-constrictor which lives on the land. It has 

 a hideous appearance, broad in the middle, and tapering 

 abruptly at both ends. We did not learn from the natives 

 that anacondas over twenty feet long had been seen on the 

 Napo, but specimens twice that size are found on the Ama- 

 zon. Land boas do not often exceed fifteen feet in length. 

 Gangs of the large howling monkeys often entertained 

 us with their terrific, unearthly yells, which, in the truthful 

 language of Bates, " increased tenfold the feeling of in- 

 hospitable wildness which the forest is calculated to in- 

 spire." They are of a maroon color (the males wear a 

 long red beard), and have under the jaw a bony goitre — 

 an expansion of the os hyoides — by means of which they 

 produce their loud, rolling noise. They set up an unusual 



chorus whenever they saw us, scampering to the tops of 

 the highest trees, the dams carrying the young npon their 

 backs. They are the only monkeys which the natives have 

 not been able to tame. Vast numbers of screaming par- 

 rots and macaws flew over our heads, always going in pairs 

 and at a great height. Groups of " gypsy -birds" were 

 perched on the trees overhanging the river, and black 



