G. GENERAL NATURAL HISTORY AND ZOOLOGY. 251 



in North America, and a renewal could not be obtained from 

 either Asia or Europe, as these were cut off by water, but the 

 concomitant elevation of Panama and other portions of Mid- 

 dle America furnished a bridge over which travel could be 

 accomplished. In this view is explained the preponderance 

 of South American types in the post-pliocene period, since, of 

 the remains from the Port Kennedy cave, out of thirty-four 

 we have eleven belonging to purely South American forms, 

 eleven genera common to both hemispheres, and nine of 

 doubtful position. 



Again, a further modification of the fauna has been effect- 

 ed by the change of level which took place between the time 

 of the introduction of the post-pliocence fauna and the pres- 

 ent period, this consisting in an extensive submergence of 

 land, especially in arctic latitudes. This, according to Pro- 

 fessor Dana, as quoted by Professor Cope, near Montreal was 

 450 feet or more, and in the arctic regions 1000 feet. This 

 descent of level Professor Dana considers to have been the 

 cause of the melting of the glacial ice, the stratification of 

 the drift, the deposition of gravels, and elevation of temper- 

 ature, all these changes naturally preceding the introduction 

 of post-glacial fauna from a warmer region. The Champlain 

 epoch is regarded as opening the post-pliocene, and its fauna 

 to be represented by the walrus, which extended its range to 

 Virginia, the reindeer, reaching to New Jersey, and by the 

 white whale. Proc, Amer. Phil, Society ', 1871, 75. 



FOSSIL MAMMALS OF CALIFORNIA. 



In a recent communication to the Academy of Natural Sci- 

 ences, by Professor Leidy, attention was invited to certain 

 teeth of fossil mammals forwarded to him for examination by 

 Professor Whitney. One of these was a fragment belonging 

 to the Mastodon americanus, obtained from a depth of eighty 

 feet beneath the basaltic lava of Table Mountain, Tuolumne 

 County, California, where it was found associated with the re- 

 mains of human art. There was also a molar of a large fossil 

 horse found sixteen feet below the surface on Gordon Gulch. 

 Two other teeth, somewhat similar in character, were deter- 

 mined as belonging to the species of ProtohippiLS. In other 

 specimens Dr. Leidy found evidences of the existence of a 

 gigantic animal of the camel tribe, allied to the llama. 2 D, 

 1871,50. 



