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University of California Publications. 



[Geology 



there are none common to other regions, it is necessary to base 

 correlation on the maxima of genera. For comparison with the 

 Martinez fauna the following important localities have been 

 selected : the Gulf states, the Atlantic states, the London and 

 Paris Basins and the Sind district of Western India. 



Compared with these, the fauna of the Martinez Group is 

 seen to be a distinct unit. Of the forty-nine genera listed, only 

 twenty-two could be found in the literature on the Eocene of the 

 Gulf and Atlantic states. No species were found in common, yet 

 several were somewhat similar. This fauna has its closest affini- 

 ties with that represented in the Midway of the Gulf states and 

 the Aquia stage of Maryland and Virginia. The correspondence 

 to the Aquia is, however, less marked than to the Midway. Pro- 

 fessor Clark* considers the Aquia and Nanjemoy together to rep- 

 resent both the upper and lower substages of the Chickasawan of 

 the Gulf states, and also he considers it questionable whether the 

 Eocene is represented by any beds in the Middle Atlantic slope 

 older than the Chickasawan. The fauna of the Tejon group 

 bear a closer similarity to both the Aquia and Chickasawan than 

 does the Martinez. Since the Tejon overlies the Martinez, it 

 would seem very probable that if any correlation of the latter 

 can lie made at all, it would best be made with a portion of the 

 Midway as represented in the Gulf states, and with that portion 

 of the lower Eocene which is not represented in the Maryland 

 and Virginia regions. Hence, the Martinez may represent some 

 portion or all of the lower quarter of the Eocene. 



The similarity of the Martinez fauna to that of the London 

 and Paris Basins is less marked. Sixteen out of the forty-nine 

 genera are common to the Eocene of the London Basin, and the 

 fauna corresponds more closely to that of the Thanet Sands or 

 lower Eocene. Fifteen genera were found corresponding to those 

 in the Eocene of the Paris Basin, and bore the closest resemblance 

 to the Bracheux beds, which are considered to be lower Eocene. 



In the Eocene fauna listed by Mr. W. T. Blanfordf in bis 

 memoir on the Geology of the Western Sind, nine genera, but 

 no species, Avere found which occur also in the Martinez group. 



*Eept. Maryland Geol. Sur. Eocene. W. B. Clark, p. 84, 1901. 

 tMemoirs of the Geological Survey of India, Vol. XVII, pp. 1-200, 1880. 



