A LAND OF SKELETONS 79 
the depletion of the fauna and flora of Argentina as one 
of the unsolved problems of science. 
In regard to other formations, it must suffice to say that 
at Parana, and also on the coast at Monte Hermoso, near 
Bahia Blanca, there occur certain Tertiary deposits which 
are evidently somewhat older than the Pampean beds, 
although containing a closely allied fauna. The most 
interesting feature connected with this formation (which 
may probably be correlated with the upper Pliocene of 
Europe) is that the mammals are for the most part of 
smaller size than their relatives of the Pampean, this being 
especially shown by the glyptodons, and by those ground- 
sloths known as scelidotheres, which are near allies of the 
mylodons. When we reach the still older beds of Santa 
Cruz, in Patagonia, which are probably of Miocene age, we 
find not only this diminution in the size of the mammals 
still more marked, but we likewise notice the disappearance 
of all the northern forms, such as deer, horses, guanacos, 
and mastodons, thus showing that we have reached the 
period when South America was disconnected from the 
northern half of the continent, and possessed an absolutely 
peculiar fauna. Instead of glyptodons with a shell of eight 
or ten feet in length, we meet with species in which the 
carapace did not measure more than a yard; while in place 
of mylodons bigger than a rhinoceros we are confronted with 
a species not so large as a Highland sheep. The camel-like 
Macrauchenia was likewise represented by several much 
smaller allies, while the various species of Nesodon, which 
represented the gigantic Zoxodon of the Pampean, were either 
small or moderate-sized animals. Somewhat curiously, there 
were, however, several kinds of gigantic flightless birds, 
which are quite unknown in the higher beds, and appear 
to have been allied to the existing seriema of Brazil. 
