736 



IDAHO MINING DISTRICTS. 



having an outside distribution. The following table shows graphically 

 the distribution of these species : 



Distribution of the flora of the Payette formation. 



From this table it appears that 9 of the 10 species are found in the 

 lone formation (auriferous gravels) of California, or the Miocene of 

 Bridge Creek and the John Day Valley, Oregon, and that 6 of the 

 species have never before been found outside of these places. Of the 

 3 species also reported from the Green River group, Sequoia angusti- 

 folia, as reported from California, is probably not the same as the 

 original from Nevada, as stated in the systematic portion. Salix 

 angusta is open to more or less question, being difficult of positive 

 identification at all times. The remaining species, Ficus ungeri, 

 appears to be found in the Green River group and the Payette. Acer 

 trilobatum productum is doubtfully identified from the collection 

 under discussion, and is therefore entitled to but little consideration. 



Several of the species here described as new to science are related, 

 in some cases closely, to certain Miocene species. Thus, Quercus ida- 

 hoensis is close to Q. consimilis Newb. ; Populus occidentalis is related 

 to P. balsamoides Gopp. ; Quercus simulata is somewhat like Q. sim- 

 plex Newb. ; Myrica lanceolata and Celastrus lindgreni are clearly 

 related to species not yet published from the Lamar flora of the Yel- 

 lowstone National Park. 



The evidence of the fossil plants points, therefore, to the Upper 

 Miocene age of the Payette formation, a view which is confirmed by 

 the stratigraphy. In fact, the close relation brought out between this 

 flora and that of Bridge Creek and John Day Valley and the fact 

 that the western limit of these beds as now explored is in the direc- 

 tion of these localities make it more than possible that they may be 

 parts of a formation of wide extent. 



