A LAND OF SKELETONS 15 
The rich black alluvial mud of the Pampas, which, as 
we have seen, is entirely of fresh-water origin, is, how- 
ever, the tomb of thousands, if not millions, of the 
skeletons and bones of a host of extinct animals, which 
tell us that the country was once inhabited by a fauna 
stranger than that found in any other part of the world at 
any epoch of its history. While many of these extinct 
creatures were allied to the existing South American 
mammals, although of vastly greater bodily size, others, of 
equally gigantic dimensions, were quite unlike all known 
animals, either living or extinct. As some of these extinct 
mammals are noticed in the next article, I make but brief 
mention of them here. It may be observed, however, that, 
while the gigantic glyptodons were the representatives of 
the diminutive armadillos of to-day (although some of the 
latter flourished side by side with their huge cousins), 
the megalothere, which rivalled an elephant in bulk, together 
with its allies the mylodons, were akin both to the sloths 
and the ant-eaters of Brazil, and as they were certainly 
terrestrial in habits, they are called ground-sloths. From 
the structure of these animals, which were evidently adapted 
to sit up on their massive haunches and tear down the 
branches of trees with their powerful front claws, it may 
be inferred that the physical features of this part of 
Argentina were once very different from what they 
are at present, and that in place of continuous tracts of 
unbroken grassy plain there were probably large areas 
of forest-land, as in Brazil at the present day. In these 
forest tracts probably wandered the two species of mas- | 
todons which were the contemporaries of the ground- | 
sloths; but the existence at the same time of several ‘ 
species of horses (some closely akin to living species, 
while others were markedly distinct) seems to point to 
