ro6 



University of California. 



I Vol. 2. 



of 



Placunanomia macroschisma, Desh. 



Mytilus edulis. Linn 



Cerithidea californica, Hald. 



Acmcsa mitra, Esch 



Crepidula rugosa, Nutt. {off.) 



6. Pecten cequisiilca.tus,G&rp. (con/".)... 



7. Pecten hastatus, Sowb. (conf) 



S Chrysodomus dims, Reeve 



Yolrfia impressa , Con 



Pec t unculus patu/us, Con 



Trochita inomata, Gabb 



Siiuim scopu/osnm, Con. (conf.) .... 

 Fusus nov. sp. (a) 



14. Ftisus nov. sp. (b) 



15. Patelloid nov 



16. Nassa (?) nov. sp 



17. Ancillaria nov. sp 



18. Cytherea nov. sp. (a) 



19. Cytherea nov. sp. (£) 



20. Bittium nov. sp, (?) 



21. Crepidula sp 



22. Ostrea sp 



23. Cardium sp 



24. Cerithidea sp 



25. Tapes (?) sp 



1. 



2. 

 3- 

 4- 

 5- 



Age and Relationsliip of Fauna — In attempting to determine the 

 age of the Sooke beds, a comparison of their fauna with that now ex- 

 isting on the Pacific Coast shows that of the twenty molluscan species 

 determined, eleven, or about fifty-five per cent, are probably extinct, 

 and eight or nine are pretty certainly living. Five species could not 

 be certainly determined and should not be considered. According 

 to the law of percentages as generally used in determining the age 

 of Tertiary faunas, the nearly equal number of living and extinct 

 species makes it impossible to place the beds in either the Eocene 

 or Quaternary. The number of species listed being small, we can 

 not place much dependence in the percentage of living species for 

 accurate determination of the age; it is hardly probable, however, 

 that the Miocene would contain forty-five per cent, of living species, 

 that number indicating a period nearer the present time. 



Regarding the trustworthiness of the percentage method as 



