338 CALIFORNIA ACADEMY OF SCIENCES. 



overlaid conformably by a series of calcareous sandstones 

 and conglomerates, which are quite fossiliferous. As this 

 series occupies structurally the same position that has been 

 assigned to the Transition beds of the Santa Cruz Mount- 

 ains it will be of interest to compare their faunas. 



Among the fossils collected in the ridge over the San 

 Fernando tunnel the following have been specifically de- 

 termined: 



Amusium cauriuum Gould. Nassa Californica Conrad. 



Calyptra tilosa Gabb? Neptunea humerosa Gabb. 



Cancellaria c. f. vetusta Gabb. Ostrea veatehii Gabb. 



Cardium meekianum Gabb. Pachopoma gibberosum Chemnitz. 



Chione simillima Sowerby? Liropecten estrellauum Conrad. 



Crepidula rogosa Nuttall? Pisania fortis Carpenter. 



Dentalium liexagonum Sowerby. Saxidomus gibbosus Gabb? 



Dosina jDonderosa Gray. Solen sicarius Gould. 



Drillia torosa Carpenter. Turritella cooperi Carpenter. 



Lunatia lewisii Gould. Turritella jewetti Carpenter. 



Macoma nasuta Conrad. Venericardia veuticosa Gould. 

 Myurella simplex Carpenter 



In this list of twenty-three species, fourteen are living 

 in the present fauna of that region or sixty per cent. 



S iimniary . — Based upon the above data the following 

 conclusions seem justified: 



I. A series of beds of considersble thickness and im- 

 portance and quite fossiliferous overlies the White Mio- 

 cene shale or Monterey series. 



II. The age of this series is Pliocene, but at the bot- 

 tom is transitional from the Miocene and at the top prob- 

 ably transitional in the Pleistocene. 



III. This series was laid down before the main uplift 

 which has given the Santa Cruz Mountains their present 

 structure took place. 



IV. The beginning of the period of their deposition 

 was marked by minor movements of the earth's surface. 

 Evidence of this does not always appear. 



