The Descent of Man

Most of the remnants survive on islands, such
as Madagascar and the Malayan archipelago,
where they have not been exposed to so severe
a competition as they would have been on wellstocked
continents. This group likewise presents
many gradations, leading, as Huxley remarks
(20. 'Man's Place in Nature,' p. 105.), "insensibly
from the crown and summit of the
animal creation down to creatures from which
there is but a step, as it seems, to the lowest,
smallest, and least intelligent of the placental
mammalia." From these various considerations
it is probable that the Simiadae were originally
developed from the progenitors of the existing
Lemuridae; and these in their turn from forms
standing very low in the mammalian series.
The Marsupials stand in many important characters
below the placental mammals. They
appeared at an earlier geological period, and
their range was formerly much more extensive
than at present. Hence the Placentata are gene-