Chap. Y. TWO FORMS OF UAKARI. 313 
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 Japura, I 
could not precisely ascertain ; Senhor Chrysostomo, 
however, assured me that at 180 miles from the mouth 
of this river, neither white nor red Uakari is found, but 
that a third, black-faced and gray-haired species, takes 
their place. I saw two adult individuals of Brachyurus 
rubicundus at Ega, and a young one at Fonteboa ; but 
was unable to obtain specimens myself, as the forests 
were inundated at the time I visited their locality. I 
was surprised to find the hair of the 'young animal 
much paler in colour than that of the adults, it being of 
a sandy and not of a brownish-red hue, and consequently 
did not differ very much from that of the white species ; 
the two forms, therefore, are less distinct from each 
other in their young than in their adult states. The 
fact of the range of these singular monkeys being 
so curiously limited as here described, cannot be said to 
be established until the country lying between the 
northern shore of the Solimoens and New Granada be 
well explored, but there can be no doubt of the separa- 
tion of the two forms in the Delta lands of the Japura, 
and this is a most instructive fact in*the geographical 
distribution of animals. 
