SOME EARLY MAMMALS 237 
Thus, the Tapir from Sumatra, or Central and South America, 
is the nearest living relative of the Paleothere; while, if we go 
back still further—into Jurassic times,—we must fetch mar- 
supials from Australia to match some of the little mammals 
whose jawbones are found in some of the deposits of that age. 
To the geologist and naturalist, South America and Australia 
are countries which have, as it were, lagged behind; for their 
faunas are not “up to date,” as the saying is; and thereby hangs 
a long story—into which we must not be led now,—and one 
which shows how closely the sciences of Geology, Natural 
History, and Geography are interwoven. 
As already stated, Cuvier’s great results in restoring Eocene 
animals were due, in a large measure, to the use he made of his 
principle of “correlation ;” of which he writes: “I doubt whether 
I should ever have divined, if observation had not taught me, 
that the ruminant hoofed beasts should all have the cloven foot, 
and be the only beasts with horns on the frontal bone.”! Again, 
it is found—though no one knows why—that only those hoofed 
animals which have their hoofs in one or two pairs, have horns 
in one or two pairs on the frontal bones: whilst those with 
three hoofs, if they have horns at all, have either one or two 
placed one behind the other (example, the Indian rhinoceros with 
one horn and the African two-horned rhinoceros). There must 
be secret reasons for these curious facts—who shall win im- 
mortality by discovering them? Other relationships, such as 
that between teeth and hoofs, might be given; but the above 
example is sufficient for our present purpose (see p. 7). In 
dealing with this subject, however, it should be mentioned that 
Cuvier’s law is not infallible, and does not always apply to some 
of the ancient and generalised types discovered since his day. 
' Ossemens Fossiles, tom. i. p. 184. (1834.) 
