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(Cope), remarkable for its born-like bony tubercles projecting 
out on each side from near the front end of the lower jaw. 
These became extinct, as in the Old World, before the close of 
the Miocene epoch. 
Animals more like true pigs also existed, but all of the pec- 
nary type, the oniy one which now survives on the American 
continent. If the evidence of teeth alone can be trusted, this 
form, like the tapir (and the African Hyomoschus ), is an un- 
modified remnant of the old Miocene fauna. But both at that 
period and in the Pleistocene, peccary- like animals existed in 
greater variety (as in the genus Platygonus ), and in wider 
geographical distribution than at present. It is interesting to 
note that no remains of true Sus or any of its Old World 
modifications, as the wart hog (. Phacochcerus ), and babirussa, 
or of any species of hippopotamus, have hitherto been met 
with on the American continent. And thus the American 
Bunodont Artiodactyles, instead of undergoing great and 
diverse modifications, as did the corresponding animals of the 
Old World, have been gradually dwindling and contracting to 
the two closely-allied species of peccary ( Dicotyles tajacu and 
D. labiatus ), among the smallest and most insignificant of the 
whole group. 
2. Of the Selenodont or crescentic-toothed Artiodactyles, 
the former existence in America of the long-extinct Old World 
genus Hyopotamus has been recognised by the discovery of a 
few teeth in the lowest Miocene of Dakota ; and this is remark- 
able as the only recorded instance of an American form with 
three cusps on one of the lobes of the upper molars, a very 
common character among the European Miocene Artiodactyles. 
Remains have also been found recently of various small 
ruminant-like animals, some not larger than a squirrel in size, 
to which the names Leptomeryx , Hypisodus , Hypertragulus , 
&c., have been applied. Whether these belonged to the family 
of Chevrotains or Tragulidce (improperly called pigmy musk- 
deer), or whether, as appears more probable, they were not 
rather generalised or ancestral forms of the true Pecora or 
Ruminants, is difficult to determine from the present evidence. 
Perhaps the most interesting of the American Miocene 
Artiodactyles, on account of their great abundance both in 
species and individuals, the full information which has been 
collected as to their structure, and their distinctness from any 
known forms from any other part of the world, is a family to 
which Professor Leidy applied the term Oreodontidce. They 
played the part in the North American Miocene fauna which 
the deer do now in the same country, the antelopes in Africa, 
and the sheep in Central Asia. They were in nearly all points 
of structure intermediate between the ruminants and pigs, and 
