1916] 



Packard: 



Cretaceous of Santa Ana Mountains 



145 



water faunal phase is best represented at the following University 

 of California localities: 2136, 2147, 2153, 2156, 2166, and 2170. 



The deeper-water phase of the Turritella peseaderoensis zone is 

 noteworthy for the number of species of the Volutidae and Aporrhaidae 

 that it contains. Opis triangulata commonly occurs in the shales at a 

 horizon about the middle of this zone. Several poorly preserved am- 

 monids and nautiloids occur more abundantly here than elsewhere. 



The shallower-water phase of the Turritella peseaderoensis zone 

 replaces in part the fauna from the shales below. The strata through 

 which this assemblage ranges comprise about six hundred feet of 

 sandstones, heavy conglomerates, and occasional subordinate bands 

 of shale. The following University of California localities have been 

 selected as being characteristic of this phase of the Turritella pes- 

 eaderoensis zone: 2135, 2146, 2148, 2150, 2151. 2152, 2159, 2160. 2162, 

 2167, and 2172. Crassatellites lomana and C. conradiana var. tuscana 

 together with Turritella peseaderoensis form a large proportion of the 

 fauna of a fossiliferous stratum that is traceable for a distance of 

 several miles. 



The uppermost zone is known as the Tellina ooides zone. The 

 fauna is characterized by the great abundance of specimens of Tellina 

 and occurs within the uppermost three hundred feet of the section. 

 The strata consist primarily of fine-grained sandstones. The fauna 

 from these upper beds is imperfectly known, due to the concealment 

 of much of this part of the formation by the overlying Vaqueros. 

 The fauna of this zone listed in the table below was obtained from the 

 University of California localities 2168 and 2169. 



This zone yields a large number of pelecypods and relatively few 

 gastropods. The lack of cephalopods is noteworthy, especially since 

 fragments of ammonites are frequently collected in the beds below 

 this horizon. Perissolax breviroslris is quite characteristic of the zone. 

 Meehia sella was found only within these uppermost beds, although it 

 has been reported elsewhere from the lower Chico. 



The fauna of the different zones is indicated in the table below. 

 A fifth column is given for those species whose stratigraphic position 

 is unknown. An asterisk indicates species characteristic of the zone 

 in which this convention appears. 



