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University of California Publications in Geology [Vol. 9 



Gasteropoda (continued) Nassa mendica, var. cooperi Forbes 



Drillia inermis Hinds Natica clausa Brod. & Sby. 



Lacuna compacta Carpenter Olivella biplicata Sby. 



Nassa fossata Gould Thais lima Martyn 

 Nassa mendica Gould 



MERCED OF BOLINAS BAY 



A very limited area of Merced occurs immediately west of 

 the entrance to Bolinas Bay, about twenty miles northwest of 

 the type section at Seven Mile Beach. Along the cliffs south of 

 the town of Bolinas the basal beds rest unconformably upon 

 much disturbed strata of middle Miocene age. As at the type 

 locality, the beds have been folded into a large monocline dip- 

 ping eastward at an angle of approximately twenty degrees. The 

 strike is north twenty to twenty-five degrees west. In litho- 

 logical character the formation very closely resembles the series 

 at Seven Mile Beach. Gray and light-brown fine-grained sand- 

 stones predominate, with a very small amount of clay and fine 

 conglomerate. No accurate measurement of the thickness was 

 attempted, but taking into consideration the small angle at which 

 the beds dip and the limited area over which they occur, a con- 

 servative estimate would hardly place the thickness beyond five 

 hundred feet. 



A collection of fossil marine invertebrates made principally 

 from the base of the section at Bolinas has revealed the occur- 

 rence of the following species : 



Echinodermata Gasteropoda 



Scutella interlineata Stimpson Astyris richthofeni Gabb 



Pelecypoda Drillia mercedensis Martin 



Cardium meekianum Gabb Epitonium indianorum Carpenter 



Macoma inquinata Deshayes Nassa moraniana Martin 



Macoma nasuta Conrad Nassa mendica Gould 



Modiolus rectus Conrad Natica clausa Brod. & Sby. 



Paphia tenerrima Carpenter Olivella biplicata Sby. 



Schizothaerus nuttalli Conrad Olivella intorta Carpenter 



Spisula catilliformis Conrad Thais lamellosa Gmelin 

 Spisula hemphilli Dall 



All of these species, including the most characteristic, occur 

 in the Merced Series at the type locality and show the close con- 

 nection between the two sections. 



MERCED OF ANO NUEVO BAY 



An area, similar to that at Bolinas Bay, occurs along the 

 east shore of Aho 'Nuevo Bay, about fifty miles south of the 



