THE PRIMATES. 619 
eries have led to the hypothesis, that from still older, more 
generalized types, four lines of development, respectively 
culminating in the typical Carnivores, Cetaceans, lemurs, and 
monkeys, have taken their origin. That the lemurs, though 
now restricted to Madagascar, eastern Asia, and South 
Africa, were preceded by still more generalized types on the 
American Continent, is indicated by the discovery of fossil 
bones in the Eocene beds of the Rucky Mountains, referred 
by Marsh and Cope to the Primates; Marsh stating that 
the principal parts of the skeleton are ‘‘ much as in some of 
the lemurs.” - 8 
Allied to the true lemurs is a very puzzling creature, the 
aye-aye or Chiromys, of Madagascar, whose dentition differs 
from that of all other Primates, and resembles that of the 
Rodents ; the thumb also is not truly opposable, and all the 
hind digits, except the great, toes, have claw-like nails. The 
Gaiago, of West Africa, somewhat recalls the Jnsectivora, 
while ‘‘in the more active and flexible-bodied Lemuride, 
she trunk-vertebre resemble in proportions, connections, and 
Girection of neural spines those of the agile Carnivora.” 
(Owen. ) 
The genuine Primates or suborder Anthropoidea are, im 
biief, characterized by the large, convoluted cerebral hemi- 
spheres which nearly, or in the higher apes and man, conceal! 
the cerebellum when seen from above.* ‘The ears are rounded, 
with a distinct lobule, and the two mamme are pectoral. 
These Anthropotdea are divided into two subdivisions, the 
first comprising the monkeys and apes, and the second, man. 
In the first group (Simi), the body is prone, the animal 
walking on all-fours, only the orang and gorilla walking 
partly erect; the great toe is rather short, thumb-like, and 
opposable to the fingers, while the body is very hairy. The 
monkeys of the New World have a wide septum to the nose, 
and are hence called Platyrhine ; they also have long tails. 
The little, squirrel-like, gregarious marmosets are the small- 
est of the monkeys and nearest allied to the lemurs. They 
walk on all-fours, the anterior extremities being like the 
*In the low Hapale and Cebus, however, the cerebrum projects 
vackward as far or even farther than in man (Gill). 
