PEDIGREE OF MAMMALS, 281 
several peculiarities of skull, they manifest the most 
extraordinary power of adaptation to arboreal and 
steppe-life, to land and water. The Insectivora, although 
not nearly so rich in species, offer a similar spectacle of 
adaptations by which their genera have become almost 
repetitions of the Rodents ; and the Cheiroptera (bats), 
in their most numerously represented division, may be 
regarded as a side branch of the Insectivora, if they 
have not proceeded directly from animals resembling 
the Lemuride. . 
In what geological period the monkeys were evolved 
from lemur-like forms we do not know. The few fossil 
monkeys with which we are acquainted belong to the 
higher families of apes, and pre-suppose a long series 
of ancestors. The same conjecture is forced upon us 
by the geographical isolation of the American monkeys 
from those of the Old World, which is also combined 
with considerable anatomical differences, although it 
could not occur to zoologists or comparative anatomists 
to deny their close systematic affinity. 
The relation of the lower to the higher apes requires 
further discussion, which we shall combine with our 
disquisition on the relation of man with the monkeys. 
