Cuap. XII. DISTRIBUTION OF MONKEYS. 343 
the Cebidz and Marmosets), and are, moreover, linked to the Baboons 
through intermediate forms (Macacus), and the possession of callosities 
on the breech, and other signs of blood-relationship. 
A few more words on the peculiar way in which these groups of 
monkeys are distributed over the earth’s surface. We may consider, in 
connection with this subject, the great land masses of the warmer parts 
of the earth to be four in number. 1. Australia, with New Guinea and 
its neighbouring islands ; 2. Madagascar; 3. America; 4. the Conti- 
nental mass of the Old World, comprising Europe, Africa, Asia, and the 
Islands of the Malay Archipelago, which latter are connected with Asia 
by a shallow sea, whilst they are separated from New Guinea by a 
channel of very deep water ; the shallow sea pointing to a former, but 
recent, union of the lands which it connects, the deep channel a 
complete and enduring severance of the lands which it separates. Now, 
with regard to monkeys, these four land masses seem to have had these 
animals allotted to them in the most capricious way possible, if we are 
to take for granted that the species were arbitrarily created on the lands 
where they are now found. Australia, with soil and climate as well 
adapted for Baboons as Africa, where they abound, and New Guinea, 
- with rich humid forests as suitable for Orangs and Gibbons as the very 
similar island of Borneo, have, neither of them, a single species of 
native monkey. Madagascar possesses only Lemurs, the most lowly- 
organised group of apes, although the neighbouring continent of Africa 
contains numerous species of all families of Old World apes. America, 
as we have seen, has no Lemurs, and not a single representative of the 
Old World groups of the order, but is well peopled by genera and 
species belonging to two distinct groups peculiar to the continent. 
Lastly, the Old World continental mass, with a few anomalous forms of 
Lemurs scattered here and there, is the exclusive home of the whole of 
the Pithecidz family, which presents a series of forms graduating from 
the debased Baboon to the Gorilla, which some zoologists consider to 
approach near to man in his organisation. 
What does all this mean ? Why are the different forms apportioned 
in this way to the various lands of the earth? Why is Australia with 
New Guinea destitute of monkeys, and why should Madagascar have 
stopped short at Lemurs, whilst America has gone on to prehensile- 
tailed Cebide, and the Old-World continent continued to Gibbons, 
Orangs, Chimpanzee, and Gorilla? Is it that the greater land masses 
have seen a larger amount of geological and climatal changes with 
corresponding changes in the geographical relations of species? More- 
over, why should the smaller groups of the order be confined to smaller 
areas within the greater areas peopled by the families to which they 
belong? For, it must be added, the true Lemurs are confined to 
Madagascar, the Gibbons and others to South-Eastern Asia, the dog- 
faced baboons to Africa, and, as we have seen, the scarlet-faced monkeys 
to a limited area on the Upper Amazons. May we be allowed to 
explain the absence of these animals from New Guinea with Australia, 
by the supposition that these lands were separated from South-Eastern 
Asia before the first forms of the order came into existence? If so, it 
may be concluded that Madagascar became separated from Africa, and 
