424 University of California Publications in Geology 



[Vol. 8 



SUMMARY OP PAUNAL LIST 



Species 



Echinodermata 9 



Pelecypoda 87 



Gastropoda 63 



Bryozoa 3 



Crustacea 3 



Total number of species 165 



Number of determinable molluscan species 135 



Number of Recent molluscan species 32 



Percentage of Recent molluscan species to total of molluscan and echino- 



derm species 21.2 



Percentage of Recent molluscan species to total molluscan fauna 23.5 



Percentage of Recent gastropod species in determinable gastropod fauna 11 

 Number of echinoderm and molluscan species in Lower Major faunal 



zone 76 



Number of echinoderm and molluscan species in Upper Major faunal 



zone 109 



Number of species common to San Pablo and Seutella breweriana zone.... 27 

 Number of species common to San Pablo and Santa Margarita of south.. 38 

 Number of species common to San Pablo and Etchegoin-Purissima Hori- 

 zon and including all Recent species found in the former which have 



not been found in the latter 48 



Number of species common to the San Pablo and the Lower Neocene. 

 (Includes "Temblor, Vaqueros and Monterey," not Seutella brewer- 

 iana zone) 14 



Number of new species and varieties described 72 



SUMMARY OP EVIDENCE FOR PAUNAL ZONES IN 

 SAN PABLO GROUP 



Two major faunal zones are recognizable in every section described 

 and in each are minor faunal zones. The minor faunal zones are estab- 

 lished on the following evidence: (1) Seutella gabbii is common in 

 the lower San Pablo in nearly every section known. The species is not 

 limited to the lower beds, however, as was formerly believed, for 

 occasional specimens have been found at several localities well above 

 the middle of the group. (2) Astrodapsis tumidus subsp. cierboensis 

 first appears a little above the base and ranges well up toward the 

 middle of the group; associated with it is Seutella pabloensis. (3) 

 Astrodapsis tumidus and Astrodapsis whitneyi are first found near the 

 middle of the group. On the south side of Mount Diablo the latter 



