214 University of California Publications in Geology [Vol. 10 



the same horizon, is also found well developed in the Priest Valley, 

 and that it is present north of Coalinga in beds traceable to the type 

 section of the Etchegoin of Arnold and Anderson. At all localities 

 where this association is found the stratigraphic range of the fauna 

 appears very short, and there is no repetition at other horizons of a 

 similar assemblage. A strikingly large number of the species are 

 unknown outside this zone. In it are found a coral, a brachiopod, 

 several species of Pecten unknown in other horizons. One of the 

 most characteristic forms is Pecten etchegoini Anderson and its vari- 

 eties nutteri Arnold and wattsi Arnold. It has been found that this 

 species, which has been used largely for correlation in the Pliocene, 

 has a very long range. This form occurs south of Coalinga from 

 below the Turritella nova zone to the uppermost beds of the Etchegoin 

 group, or approximately through 4000 feet of strata. Trophon ma- 

 gister Nomland, formerly thought of very limited range, has been 

 found in this zone. A number of the more recent forms are also 

 rarely found, such as Pecten hastatus, var. hindsii Carpenter, Murex 

 festivus Hinds, Trophon gracilis (Perry). 



Uppermost in the predominantly marine deposits of the Etchegoin 

 and directly below the fresh-water deposits of the Tulare a faunal 

 assemblage is found which has been named by Ralph Arnold the 

 Mya japonica zone. It is found persistently in the Kettleman Hills 

 and in the Kreyenhagen Hills. North of Coalinga a similar fauna 

 has been found in a resistant band of argillaceous tuff in the outer- 

 most foothills. In Priest Valley the zone does not occur and the line 

 of demarcation between the Etchegoin and the Tulare is distinguished 

 with difficulty. The fauna of the uppermost part of this zone is 

 mainly that of shallow-water or littoral conditions. A number of 

 species found immediately below the typical Mya japonica zone at 

 several localities are included with the fauna of that zone in the 

 accompanying list. The only species of this zone unknown in other 

 horizons is Littorina mariana Arnold and its variety L. mariana, var. 

 alt a Arnold. In most of the localities along this zone the so-called 

 fish bulbs are found in large numbers. North of Coalinga the extinct 

 horse Pliohippus proversus Merriam is found at this horizon. 



ETCHEGOIN FAUNA WEST OE THE DIABLO KANGE 

 It has already been stated that the Pliocene is present on the west 

 side of the Diablo Range in the latitude of Coalinga. The following 

 Pliocene species have been obtained on the north bank of Whalen 



