564 
MAMMALIA. 
Buffon has justly declared that these are the prettiest and most 
charming of all the Monkeys ; they are much sought after, but as 
they are very rare, few of them are seen in Europe. Isidore 
Geoffroy Saint-Hilaire speaks in the following terms of the 
Saimiri : — 
“ Its physiognomy is that of a child ; it has the same expression 
of innocence, sometimes the same sly smile, and always the same 
rapidity of transition from joy to sorrow ; it feels disappointment 
very acutely, and testifies it by crying. Its eyes become be- 
dewed with tears when it is vexed or frightened. It is prized 
by the natives for its beauty, its amiable manners, and the gentle- 
ness of its disposition. Its activity is astonishing, though its 
movements are always full of grace. It is incessantly occupied 
in play, jumping, and catching insects, especially spiders, which it 
prefers to all kinds of food.” 
Humboldt informs us that the Saimiri listens with the greatest 
attention to people who ask it questions, and that it even stretches 
out its hands towards their lips, as if to catch the words that 
escape from them. 
Genus Nocthora . — The names of Nocthora and Nyctipithecus, 
given by Fr. Cuvier and by Spix to animals of this genus, in- 
dicate their essentially nocturnal or crepuscular habits. These 
little Monkeys sleep all the day, either in the cavities of trees or 
in the midst of the thickest foliage, and it is only towards sunset 
they come forth. Their eyes are very large and phosphorescent — 
that is, luminous in the dark. Humboldt says that these Mon- 
keys are monogamous, and always live in couples ; but Spix 
assures us they go together in hands. 
The JSTocthora subsist on insects and small birds. Their voice 
is powerful, and, according to Humboldt, resembles that of the 
Jaguar. The best known species, the Douroucouli (. Nyctipithecus 
trivergatus ), takes its name from the cry it emits during the night, 
when hunting in the woods. The Hoethora inhabit the banks of 
rivers in Peru, Bolivia, Brazil, and Paraguay. 
Genus Saki . — The Sakis bear much resemblance to the Sapajous ; 
hut they are distinguished from them by their non-prehensile tail, 
which is covered with long and very bushy hair, a circumstance 
which causes them to be called Fox- tailed Monkeys. They in- 
habit thickets, solitary or in troops, and are more crepuscular than 
