152 ALLEN’S NATURALIST’S LIBRARY. 
very much ; the posterior lobes of the main brain (or cerebral 
hemispheres, which are almost always convoluted) are also 
almost always so large as to entirely cover over the cerebellum 
(or hind brain), a relation which does not exist between these 
two regions of the brain in the Lemuroidea. ‘The cerebellum, 
however, in the Howlers is slightly uncovered. The absolute 
size of the brain never, in any Ape, approaches that of Man. 
None of the Cedde@ attain the size of even the medium-sized 
Old World Apes. 
The Cedide are all arboreal, and strictly confined to the 
forest regions of Tropical America, from the southern part of 
Mexico to about the parallel of 30° S. lat. They are divided 
into four sub-families,; namely: The Douroucolis, or Night- 
Monkeys (Vyctipithecine) ; the Saki Monkeys (Lithectine) ; 
the Howlers (AZycetine); and the Capuchin Monkeys (Cedcne). 
THE NIGHT-MONKEYS. SUB-FAMILY 
NYCTIPITHECIN. 
The Night-Monkeys are small and elegant animals covered 
with long hair, and having long bushy tails, which are not 
prehensile, although they can be curled round a branch of 
a tree. The caudal vertebree in these creatures are con- 
sequently not flattened from above downward, as is the case 
in the prehensile-tailed groups, but rounded. ‘Their lower in- 
cisor teeth are set vertically and their thumb is fairly well 
developed. 
This sub-family contains three genera, the Squirrel-Monkeys 
(Chrysothrix) ; the Whaiapu-Sais, or Titis (Ca//ithrix) ; and 
the typical Night-Monkeys, or Douroucolis (Vyctipithecus). 
THE SQUIRREL-MONKEYS. GENUS CHRYSOTHRIX. 
Chrysothrix, Kaup., Thierreich., i., p. 51 (1835). 
