688 THE POPULAR SCIENCE MONTHLY. 



nearly the same. The Caviidce were especially numerous. Cercolabes, 

 Myopotamus, and Lagostomus, are also found ; and two extinct gen- 

 era, Phyltomys and Lonchopliorus. 



The Cheiroptera, or bats, have not been found in this country 

 below the middle Eocene, where two extinct genera, JYyctilestes and 

 Nyctitherium, are each represented by numerous remains. These fos- 

 sils all belong to small animals, and, so far as they have been investi- 

 gated, show no characters of more than generic importance to distin- 

 guish them from the bats of to-day. No other members of this 

 group are known from our Tertiary. In the Post-Tertiary, no ex- 

 tinct species of bats have been found in North America, but from the 

 caves of Brazil quite a number have been reported. These all belong 

 to genera still living in South America, and most of them to the fam- 

 ily Phyttostornidce. 



The Insectivores 1 date back, in this country, at least to the middle 

 Eocene. Here numerous remains occur, which have been described as 

 belonging to this order, although it is possible that some of them were 

 insect-eating Marsupials. The best-known genera are He?niacodon, 

 Centetodon, Talpavus, and PJntomacodon ; all represented by animals 

 of small size. In the Miocene, the bones of Insectivores are com- 

 paratively abundant, and the genera best determined are Ietops and 

 Leptictis. A few specimens only have been found in the Pliocene and 

 Post-Pliocene, most of them related to the moles. No extinct Insec- 

 tivores are known from South America, and no member of the group 

 exists there at present. 



The Camivora, or true flesh-eating animals, are an old type, well 

 represented in the Eocene, and, as might be expected, these early forms 

 are much less specialized than the living species. In the Coryphodon 

 beds, the genus Pimnocyon, allied to the Pterodon of the European 

 Eocene, is abundant. Another genus, apparently distinct, is Proto- 

 tomics, and several others have been named from fragmentary fossils. 

 In the middle Eocene, Carnivores were still more numerous, and many 

 genera have been discovered. One of these, Pimnofelis, was nearly 

 as large as a lion, and apparently allied to the cats, although the 

 typical Felidce seem not yet to have been differentiated. Another 

 Carnivore, of nearly equal size, was Orocyon, which had short, mas- 

 sive jaws and broad teeth. P)romocyon and Mesonyx were large 

 animals, allied to PPyoenodon. The teeth were narrow, and the jaws 

 long and slender. Among the smaller Carnivores'were Vidpavus, 

 Viverravus, Sinopa, Thinocyon, and Ziphacodon. 



In our Western Miocene, Carnivores are abundant, and make an 

 approach to modern types. The Felidw are well represented, the 

 most interesting genus being Jfachairodus, which is not uncommon 

 in the Oreodon beds on both sides of the Rocky Mountains. An 



1 Insedivora, that order of mammals which includes the existing moles, shrews, 

 hedgehogs, etc. 



