192 



R. R. MILLER 



Fig. 2. Approximate location of species of closely restricted distribu- 

 tion in western North America. Note the concentration of localized forms 

 in the Great Basin and in disrupted waters (in southern Nevada) of the 

 Colorado River drainage. Only 14 of the 43 species occur outside of those 

 areas. 



the modern forms, particularly at the generic level. It is not sur- 

 prising, therefore, that the affinities of many of the genera are 

 unknown. 



FOSSIL RECORD 



The paleontological record of Tertiary and Quaternary fishes in 

 western North America is meager. What little material is available 

 has not received critical comparative study. For the most part, the 

 available skeletal remains, particularly of the Pliocene and Pleisto- 

 cene fossils, are hardly adequate for identification below the generic 

 level or, occasionally, not even below the family. The only reason- 

 ably well-known formation is that of the Green River Eocene, which 

 involves a fauna too early in fish evolution to give much help in 

 interpreting the modern forms. Tertiary fishes have been treated 

 chiefly by Cope, and since his death in 1897, only scattered papers 

 have appeared with little attempt at evaluation or reappraisal. 

 Vigorous, organized search for and comprehensive study of late 

 Cenozoic fish fossils by students thoroughly familiar with the Recent 

 fauna is one of the urgent needs for advancing knowledge of the 

 origin, dispersal, and evolution of the present fauna. 



Fossils representing nine families have been recorded from fresh- 

 water deposits of Miocene to Pleistocene age in western North 



