CAYES AND THEIR CONTENTS 
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genus. Megalonyx and Mylodon, which follows in Pliocene 
times, were giant ground sloths almost the size of elephants, 
while Glyptotherium, another Pliocene species, had a great 
shield-like bony armour covering the whole body. The plio 
cene species -were accompanied by a great peccary (Platy- 
gonus), a llama of a very large size (Pliauchenia) and a 
number of other interesting creatures, all of which have now 
completely vanished from the northern continent. 
In the succeeding deposits from the great plains and moun¬ 
tain regions, which have been classified by Professor 
Osborn * as belonging to the lower Pleistocene series, we 
notice the remains of two large elephants (Elephas columbi 
and E. imperator), a true camel(Camelus)and two other mem¬ 
bers of the same family, the great peccary Platygonus and the 
tw r o large ground sloths, Mylodon and Paramylodon. The 
rivers were tenanted by beavers, otters, musk rats and a 
curious semi-aquatic creature about the size of a bear, called 
Castoroides. Related to some of the groups of South American 
rodents, the latter suddenly makes its appearance in the 
Pleistocene beds of eastern North America. 
Now we come to the cave deposits, which I have alluded to 
already on several occasions, and which Professor Osborn 
includes in the middle Pleistocene or Glacial series. The 
Port Kennedy cave in Pennsylvania contains no less than 
four species of the great edentate Megalonyx, also a Mylodon, 
two kinds of sabre-tooth tigers, a Mastodon, four species of 
peccaries and a tapir. In the Potter Creek cave of California 
were discovered, among others, four species of Megalonyx, a 
camel and a Mastodon. Finally, the Conard fissure of 
northern Arkansas revealed two species of sabre-tooth tigers, 
three kinds of peccaries and numerous small animals. Apart 
from a few deer bones and the remains of the curious Syrnbos, 
an animal allied to the musk ox, it contained no traces of large 
ungulates. Their presence in the district adjoining the fissure 
is, nevertheless, indicated by the sabre-tooth tigers. 
What I wish to make clear is that huge creatures requiring 
an abundance of vegetable food poured into North America, 
not only in Pliocene but also in Pleistocene times. Many 
Osborn, H. F., “ Cenozoic Mammal Horizons,” p. So. 
