MIOCENE FORMATIONS. 



28 



FAUNA. 



Doctor Mcrriam, in bis original cleKnitioii of tlie San Pablo formation, says:" 

 "The series of strata characterized by tlie presence of Antrodapiilx and Scntella 

 (Cfi/peaster) gahhi ma}-, with reference to its more important features, ))e treated 

 as a distinct foi'iiiation, and will be referred to in this paper as the San Pablo 

 formation." ^^y definition, therefore, the formation is limited in a general way 

 to the zones of the above-mentioned echinoderms. In most of the localities where 

 the formation has been recognized, at least one of these forms has generally 

 been detected. Ostrea titan. Tainioxmna (jreguria., Paendociirdhiin gaJihi^ Clionm 

 lnJclii'ri. a small OcinAra, and several species of Pecfen are also commonly found 

 in its fauna. 



According to Mci'i'iam the fauna of the San Pal)lo is known so far bv al)()ut 

 tifty species, of which nearly one-third are peculiar to this formation, about one- 

 fourth are known also from the Contra Costa County Miocene, and oii(>-sixth from 

 the Merced; while of the total number a little less than one-half are (>xtinct. Tlie 

 writer has noted several San Pablo species extending down into the A'aqueros (lower 

 Miocene); while his estimate of the extinct species is about fiT) per cent, rather tiian 

 a little less than 50 per cent as gixen \t\ Mcrriam. 



Pccten fauna. — The Pecten fauna of the San Pablo, and its sui)posc(l ccjuivalents 

 in age, consists of the following species: Pecti-n andcrisoni. P. Cdo-seimis.^ J', cranaieardo 

 and its variety kani/'lto/t/, J', d/'xeus, P. eJdridgcl^ P. extrellanus and vars. rataUn» 

 and ti^'-mimis, P. {Ilirini.tes) gi.gaiitfKS. P. Iiasfatux var. hericiux. P. nutter!, P. i_>u'en'u 

 P. j>aJ>hienxix, P. 2)<'droanux. 



The following species of more or less uncertain status may occur in the San 

 Pablo or its equivalents: P. carrizoenHis.^ P. cerroxenxix yur. mendenhalll, P. diUeri. 

 P. _fucan>/x, P. keep/', I'. neaJienxis., P. jrropatulax. 



The following fossils have been found in the San Pablo formation at San Pablo 

 Bay, Kirker Pass, and other localities in the Mount Diablo region. 



LiM of , San Pahlo foriniilion iuj)j>fr Miaci'iie) fo-'^sils.'' 



[Those markerl with an asterisk (*) have been fouiui by the writer at the type locality, those followed by (C) are supposed 

 to be characteristic, and those followed by (L) also occur in the recent fauna of the coast. 1 



ECHINOIDK.V. 



*Asterias remondi Gablj (C) . 

 *A.strodapsis tuniidns Remoml (C). 

 *Astrodapsis whitneyi Remond (C). 

 Astrodap.sis n. sp. Merriam (('). 

 Scutella (Clypea,ster) gabbi Ileniond (C). 



PELECYPODA. 



*Cardiuin (cf. ) quadrigenariura Conrad (L). 

 Cyre.na calit'ornica Gabb. 

 Dosinia ponderosa Gray (L). 

 Gari alata Gabb (C) . 

 *Glyeymeris (+.-\xineal ^ji. 



i'ELKcvpoD.\ — c-Diitinued. 



Macoiiia iiasnta Conrad (L). 

 *Mactra calit'ornica Conrad (?) (L). 

 Mactra falcata Goulil ( L) . 

 Modiolus sp. (C ? I. 

 *Mulinia densata (iabb (C). 

 Mytilnsisp. (C?). 

 Ostrea bourgeosii Gabb (C). 

 Ostrea titan Conrad (C). 

 * Pecten andersoni n. sp. 

 *Pecten pabloensis Conrad (C). 

 *Pecten crassicardo Conrad. 

 Pinna alamedensis Yates. 



"Merriam. J. C, 1.19S. p. 113, 



("Turner, H. W., .lour. Geol., vol. 6, pp. 483 et seq., from which a part of this list Is copied. 



