1913] Dickerson: Fauna of Eocene at Marysvillc Unites 259 



In this note Watts referred to the sedimentary beds and recog- 

 nized their geographic relation to the central igneous rocks. ' ' In 

 ascending the most southerly peak from the Moody ranch patches 

 of light colored sand toward the base of the mountain mark the 

 sedimentary formation and the coal measures. A few fragments 

 of fossiliferous rock, showing Cretaceous fossils may be found on 

 a portion of the slope. The best exposure of sedimentary rocks 

 was seen at the base of the West Butte about a mile from the 

 village of that name." He recognized an unconformity between 

 the white sandy formation, dip about 15° S.W. and the under- 

 lying "Cretaceous" shales and clayey sandstone, dip 70° S.W. 

 A partial list of fossils identified by Cooper was given. Most 

 of these were recognized as occurring in "Cretaceous B" of 

 Gabb. Through the courtesy of State Mineralogist Storms, the 

 writer examined this collection and redetermined some of the 

 species. The species which were redetermined are given in 

 parenthesis after Cooper's determinations. 



Leda gabbi Conrad 

 Lunatia hornii Gabb 

 Olivella mathewsonii Gabb 

 Nucula solitaria Gabb 

 (Nucula cooperi, n.sp.) 

 Nassa cretacea Gabb 

 Turritella uvasana Gabb 

 Turritella merriami, n.sp.) 

 Turritella chieoensis Gabb 

 (Turritella merriami, n.sp.) 

 Meretrix hornii Gabb 

 Galerus excentrieus Gabb 

 Cardita veneriformis Gabb (prob- 

 ably the young of Cardita 

 planicosta) 



Ostrea idriaensis Gabb 



Corbula parilis var(?) Gabb 



Mysia polita Gabb 



Modiola cylindrica Gabb 



(Modiola cylindrica Gabb is prob- 

 ably an incorrect determina- 

 tion.) 



Cardita planicosta Lam. 



Area hornii Gabb 



Cardium translucidum Gabb 



(Cardium dalli, n.sp.) 



Dentalium, sp. 



Morio tuberculatus Gabb 



Arehiteetonica hornii Gabb 



(Architectoniea weaveri, n.sp.) 



Cucullaea, sp. 



Dr. J. 6. Cooper 3 described the new species collected by 

 Watts on the west side of West Butte, discussed the conditions 

 of deposition and suggested that the strata were Eocene, al- 

 though he used "Cretaceous B" as a synonym in some of the 

 descriptions of new species. All of these descriptions are given 

 at end of this paper and most of the species are refigured. Cooper 

 wrote at a time when the debate concerning the age of the 



3 Cooper, J. G., Catalogue of California Fossils, Bull. No. 4, Cali- 

 fornia State Mining Bureau, Sept., 1894, pp. 36-45. 



