TWO FORMS OF UAKARI 443 



vessel, a large schooner. When we reached the mouth 

 of the Rio Negro, we had to wait four days whilst the 

 custom-house officials at Barra, ten miles distant, made 

 out the passports for our crew, and during this time the 

 schooner lay close to the shore, with its bowsprit secured 

 to the trees on the bank. Well, one morning, scarlet- 

 face was missing, having made his escape into the forest. 

 Two men were sent in search of him, but returned after 

 several hours' absence without having caught sight of 

 the runaway. We gave up the monkey for lost, until 

 the following day, when he re-appeared on the skirts of 

 the forest, and marched quietly down the bowsprit to his 

 usual place on deck. He had evidently found the forests 

 of the Rio Negro very different from those of the delta 

 lands of the Japura, and preferred captivity to freedom 

 in a place that was so uncongenial to him. 



A most curious fact connected with this monkey is 

 the existence of an allied form, or brother species, in a 

 tract of country lying to the west of its district. This 

 differs in being clothed with red instead of white hair, 

 and has been described by Isidore Geoffroy St. Hilaire 

 (from specimens brought to Paris in 1847 by the Comte 

 de Castlenau) as a distinct species, under the name of 

 Brachyurus rubicundus. It wholly replaces the white 

 form in the western parts of the Japura delta : that is 

 to say, in a uniform district of country, 150 miles in 

 length, and sixty to eighty in breadth, the eastern half 

 is tenanted exclusively by white Uakaris, and the western 

 half by red ones. The district, it may be mentioned, 

 is crossed by several channels, which at the present time 

 doubtless serve as barriers to the dispersal of monkeys, 

 but cannot have done so for many centuries, as the 

 position of low alluvial lands, and the direction of channels 

 in the Amazons Valley, change considerably in the course 

 of a few years. The red-haired Uakari appears to be 

 most frequently found in the forests lying opposite to 

 the mouth of the river which leads to Fonteboa, and 

 ranges thence to the banks of the Uati-parana, the most 

 westerly channel of the Japura, situated near Tunantins. 

 Beyond that point to the west there is no trace of either 

 the red or the white form, nor of any other allied species. 

 Neither do they pass to the eastward of the main mouth 

 of the Japura, or to the south shore of the Solimoens. 

 How far they range northwards along the banks of the 



