UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGICAL SCIENCES 



Vol. 13, No. 5, pp. 133-174, plates 1-8 May 10, 1922 



THE BRIONES FORMATION OF MIDDLE 

 CALIFORNIA 



BY 



PARKER D. TRASK 



CONTENTS 



PAGE 



Introduction and acknowledgments 134 



Areal distribution of Briones formation 135 



Description of the formation 136 



Fauna : 139 



Complete list of known species from the Briones with their geologic range 141 



Statistical summary of faunal list 143 



Relation of the Briones fauna to the Monterey fauna 144 



Relation of the Briones fauna to the San Pablo fauna 144 



Description of species 147 



Leda furlongi, n.sp 147 



Pecten (Lyropecten) ricei, n.sp 148 



Pecten (Lyropecten) vickeryi, n.sp 148 



Pecten (Pecten) raymondi brionianus, n.var 148 



Pecten (Pecten) andersoni gonicostus, n.var 149 



Modiolus gabbi subconvexus, n.var 149 



Modiolus veronensis, n.sp 150 



Cyrena (Corbicula) diabloensis, n.sp 150 



Cardium corbis, n.var? 150 



Venus brioniana, n.sp 151 



Tivela merriami, n.sp 151 



Antigona willisi, n.sp 152 



Spisula falcata brioniana, n.var 152 



Calliostoma obliquistriata, n.sp 153 



Sinum (Sigaretus) trigenarium, n.sp 153 



Nassa whitneyi, n.sp 154 



Siphonalia rodeoensis, n.sp 155 



Trophon daviesi, n.sp 155 



Trophon gracilis clarki, n.nom 156 



Acanthina perrini, n.sp 157 



Koilopleura, n.gen 157 



Koilopleura sinuata, (Gabb) 158 



Oliva simondsi, n.sp 159 



Key to localities 159 



