268 



University of California 



Publications. 



[Geology 



known to lie in contact, but when the faunas of the two are com- 

 pared that of the Merced is found to be younger. That 

 is, there are less forms common to the Monterey and a larger 

 per cent, are living to-day on the coast than is the case with the 

 San Pablo. Out of the total number of species in the latter 

 twenty are common to the Merced. 



So far in correlating the San Pablo it has been referred to 

 the Pacific Coast localities. Here many species are identical but 

 when a comparison is made with the Tertiary faunas of the 

 Atlantic states and Europe, correlation has necessarily to be based 

 upon the maxima of genera. The areas selected for correlation 

 were the Maryland and Virginia districts and Florida ; and in 

 Europe the district of Touraine, in France ; the Vienna Basin 

 and the Pliocene of England and Italy. 



In correlating with the faunas of the Maryland and the 

 Virginia Miocene, no distinction was made between the upper 

 and the lower divisions. The entire Miocene fauna was consid- 

 ered. Nineteen genera were found in common but no species. 

 No marine Pliocene forms Avere available for comparison, so 

 correlation is made with the Caloosahatchie formation or the 

 Pliocene of Florida. Twenty-nine genera were found to be 

 common to the San Pablo and no species. Very little satisfac- 

 tion is gained from the correlation with the European Pliocene. 

 In the Vienna Basin only five genera were found common, in the 

 Miocene from the district of Touraine, France, only three genera 

 are common, and in the Pliocene of Italy only two. In the Plio- 

 cene of England twelve are common. The evidence obtained 

 here is inconclusive. 



The following table shows the relation of the San Pablo to 

 the Miocene and Pliocene, and to the recent fauna on the Pacific 

 Coast of North America : 



Number of San Pablo species 73 



In Monterey 21 = 28.7% 



In the Merced 20 = 27.4% 



Living 41 = 56% 



According to the classification of Lyell used in dividing the 

 Tertiary on the percentage of living species it would be impos- 

 sible to assign the San Pablo to the Miocene. The large number 



