198 
THE DESCENT OF MAN. 
Part I. 
evolution, will grant that the two main divisions of the 
Simiadse, namely the Catarhine and Platyrhine mon- 
keys, with their sub-groups, have all proceeded from 
some one extremely ancient progenitor. The early 
descendants of this progenitor, before they had diverged 
to any considerable extent from each other, would still 
have formed a single natural group ; but some of the 
species or incipient genera would have already begun 
to indicate by their diverging characters the future 
distinctive marks of the Catarhine and Platyrhine divi- 
sions. Hence the members of this supposed ancient 
group would not have been so uniform in their dentition 
or in the structure of their nostrils, as are the existing 
Catarhine monkeys in one way and the Platyrhines in 
another way, but would have resembled in this respect 
the allied Lemuridse which differ greatly from each 
other in the form of their muzzles , 14 and to an extra- 
ordinary degree in their dentition. 
The Catarhine and Platyrhine monkeys agree in 
a multitude of characters, as is shewn by their unques- 
tionably belonging to one and the same Order. The 
many characters which they possess in common can 
hardly have been independently acquired by so many 
distinct species; so that these characters must have 
been inherited. But an ancient form which possessed 
many characters common to the Catarhine and Platy- 
rhine monkeys, and others in an intermediate condition,, 
and some few perhaps distinct from those now present 
in either group, would undoubtedly have been ranked, 
if seen by a naturalist, as an ape or monkey. And as 
man under a genealogical point of view belongs to the 
Catarhine or Old World stock, we must conclude, how- 
14 Messrs. Murie and Mivart on the Lemuroidea, ‘Transact. Zoology 
Soc.’ yoI. vii. 1869, p. 5. 
