330 
ANIMALS OF EGA. 
Chap. Y. 
given the striking case of the white and red-haired 
Uakaris. If these two forms, which are considered by 
the most eminent naturalists as distinct species, have 
originated, as the facts of their distribution plainly tell 
us they have, from one and the same stock, why may 
not the various species of Lemurs, of Baboons, of Gib- 
bons, and so forth, given the necessary amount of time 
and climatal changes, have originated in the same way ? 
And if we can thus account for the origin of the species 
of one genus, on what grounds can we deny that the 
genera of the same family, or the families of the same 
order, have also proceeded from a common ^tock ? I 
throw out these suggestions simply for the consideration 
of thoughtful readers, but must add, that unless the 
common origin, at least, of the species of a family be 
admitted, the problem of the distribution of monkeys 
over the earth's surface must remain an inexplicable' 
mystery, whilst, if admitted, a flood of light illuminates 
the subject, and promises an early solution to honest 
and patient investigation. These questions, also, show 
how interesting and difficult are the problems which 
Natural History, granted the right and ability of the 
human mind to deal with them, has to solve. 
It is a suggestive fact that all the fossil monkeys 
which have been found in Europe and America, belong 
in each case to the types which are still peculiar to the 
continent which they inhabit. The European fossils are 
all of the Pithecidse family, the South American all 
belong to the Cebidae and Marmoset families. The 
separation of the two continental masses (at least of 
their warm zones) must therefore be of great geological 
