160 F. E. PEABODY AND J. M. SAVAGE 



major contributions outside his immediate field, it is probably true 

 that the paleontologist and even the geologist may profit from a 

 closer look at biological data. It is the general purpose of the present 

 paper to demonstrate the advantages of a many-sided approach to 

 the problems of origin and dispersal of the biota of far western North 

 America. Attention is focused on the late Cenozoic era because the 

 historical events of that time are most completely documented and 

 because these events produced the major patterns of origin and 

 distribution of modern species. 



Distribution diagrams are based on the treatise by Stebbins 

 (1954), with some emendations by the junior author. The distribu- 

 tion patterns are selected to illustrate best the relationship to the 

 coastal corridor. It is believed that the pattern of present distribu- 

 tion of species provides a general indication of the point of origin 

 with respect to the geologically recent corridor. Obviously, fluctua- 

 tions must have taken place in the past as at present, as witness the 

 northward advance of southern species and northward retreat of 

 boreal species which are presently being documented across North 

 America. 



THE FOSSIL RECORD 



Fossil remains of amphibians and reptiles are rare in North 

 America west of the Mississippi and extremely rare in the far west. 

 Some indication of the fact is afforded by the paucity of citations 

 from bibliographic sources. For the 41 -year period from 1913 to 

 1954, the journal Copeia, of the American Society of Ichthyologists 

 and Herpetologists, contains only four papers describing Pleistocene 

 reptiles, and only three papers on Pliocene reptiles (Reed, 1956). 

 The more complete coverage in the Camp bibliographies of verte- 

 brate paleontology over the 20-year period 1928-1948 includes ap- 

 proximately eleven papers on amphibians, none concerning far 

 western North America, and approximately sixteen papers on rep- 

 tiles, none concerning the far west (Camp et al., 1940-1953). More 

 current literature includes a few but important contributions, for 

 example, the description of the salamander, Paleotaricha, from the 

 Oligocene of Oregon (Van Frank, 1955), and contributions by 

 Bayard H. Brattstrom (particularly 1954, 1955) and Richard G. 

 Zweifel (1955, 1956) on the herpetofauna of the Tertiary and Pleisto- 

 cene. In general the described fossils older than the late Pleistocene 



