332 ANIMALS OF NEIGHBOURHOOD OF EGA. Cuap. XII. 
eyes. They sat gravely and silently in a group, and altogether presented 
a strange spectacle. These red-faced apes belonged to a species called 
by the Indians Uakarf, which is peculiar to the Ega district, and the 
cage with its contents was being sent as a present by Senhor Chrysos- 
tomo, the Director of Indians of the Japura, to one of the Government 
officials at Rio Janeiro, in acknowledgment of having been made 
colonel of the new national guard. They had been obtained with 
great difficulty in the forests which cover the lowlands, near the 
principal mouth of the Japurd, about thirty miles from Ega. It was 
the first time I had seen this most curious of all the South American 
monkeys, and one that appears to have escaped the notice of Spix and 
Martius. I afterwards made a journey to the district inhabited by it, 
but did not then succeed in obtaining specimens; before leaving the 
country, however, I acquired two individuals, one of which lived in my 
house for several weeks. 
The scarlet-faced monkey belongs, in all essential points of structure, 
to the same family (Cebidz) as the rest of the large-sized American 
species ; but it differs from all its relatives in having only the rudiment 
of a tail, a member which reaches in some allied kinds the highest grade 
of development known in the order. It was so unusual to see a 
nearly tailless monkey from America, that naturalists thought, when 
the first specimens arrived in Europe, that thé member had been 
shortened artificially. Nevertheless, the Uakari is not quite isolated 
from its related species of the same family, several other kinds, also 
found on the Amazons, forming a graduated passage between the 
extreme forms as regards the tail. The appendage reaches its per- 
fection in those genera (the Howlers, the Lagothrix, and the Spider 
Monkeys) in which it presents on its under surface near the tip a naked 
palm, which makes it sensitive and useful as a fifth hand in climbing. 
In the rest of the genera of Cebidz (seven in number, containing thirty- 
eight species), the tail is weaker in structure, entirely covered with 
hair, and of little or no service in climbing, a few species nearly related 
to our Uakari having it much shorter than usual. All the Cebidze, both 
long-tailed and short-tailed, are equally dwellers in trees. The scarlet- 
faced monkey lives in forests which are inundated during great part of 
the year, and is never known to descend to the ground; the shortness 
of its tail is therefore no sign of terrestrial habits, as it is in the 
Macaques and Baboons of the Old World. It differs a little from the 
typical Cebidz in its teeth, the incisors being oblique and in the upper 
jaw converging, so as to leave a gap between the outermost and the 
canine teeth. Like all the rest of its family, it differs from the monkeys 
of the Old World, and from man, in having an additional grinding-tooth 
(premolar) on each side of both jaws, making the complete set thirty-six 
instead of thirty-two in number. 
The white Uakarf (Brachyurus calvus) seems to be found in no other 
part of America than the district just mentioned, namely, the banks of 
the Japurd, near its principal mouth ; and even there it is confined, as 
far as I could learn, to the western side of the river. It lives in small 
troops amongst the crowns of the lofty trees, living on fruits of various 
kinds. Hunters say it is pretty nimble in its motions, but is not much 
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