ix.] PALEONTOLOGY AND EVOLUTION. 203 



two exceptions to the last rule, but they are readily 

 susceptible of explanation. Thus, in Australia, the 

 later Tertiary mammals are marsupials (possibly with 

 exception of the Dog and ,a Eodent or two, as at 

 present). In Austro-Columbia the later Tertiary fauna" 

 exhibits numerous and varied forms of Platyrrhine Apes, 

 Eodents, Cats, Dogs, Stags, Edentata, and Opossums ; 

 but, as at present, no Catarrhine Apes, no Lemurs, no 

 Insectivora, Oxen, Antelopes, Ehinoceroses, nor Didel- 

 phia other than Opossums. And in the wide-spread 

 Arctogseal province, the Pliocene and ]ater mammals 

 belong to the same groups as those which now exist in 

 the province. The law of succession of types, therefore, 

 holds' good for the present epoch as compared with its 

 predecessor. Does it equally well apply to the Pliocene 

 fauna when we compare it with that of the Miocene 

 tpoch ? By great good fortune, an extensive mammalian 

 fauna of the latter epoch has now become known, in four 

 very distant portions of the Arctogseal province which 

 do not differ greatly in latitude. Thus Falconer and 

 Cautley have made known the fauna of the sub-Hima- 

 layas and the Perim Islands ; Gaudry that of Attica ; 

 many observers that of Central Europe and France ; 

 and Leidy that of Nebraska, on the eastern flank of 

 the Eocky Mountains. The results are very striking. 

 The total Miocene fauna comprises many genera and 

 species of Catarrhine Apes, of Bats, of Insectivora ; of 

 Arctogseal types of Rodentia; of Proboscidea; of equine, 

 rhinocerotic, and tapirine quadrupeds ; of cameline, 

 bovine, antilopine, cervine, and traguline Euminants ; of 

 Pigs and Hippopotamuses ; of Viverridce and Hycenidce 

 among other Carnivora ; with Edentata allied to the 

 Arctogseal Orycteropus and Manis, and not to the 

 Austro-Columbian Edentates. The only type present 

 in the Miocene, but absent in the existing, fauna of 



