MIOCENE PECTENS. 83 



7'. (oxIi'i-Kom ranges from the lower to the mkldle (and prol)al)l3' upper) 

 Miocene. At locality No. 9 (L. S. J. U. Geol. Survey), on "Tutl' Hill," U miles 

 southeast of Stanford University. P. anderKoiil is associated with the following 

 species: Pecten hranneri^ Chione n. sp., Phaeolden aviitllinnatim^ Venus {of. )j/erte7iuls; 

 Tei't-'hrntella (?) n. sp., Glyeymeris sp., and Balamis sp. {of.) eatrattmvus. At 

 locality No. -i, not far from but stratigraphically considerably above No. 9, we 

 find /^. andersioni ^'\i\\ the the following: Agaiioiiuiharl-crianum, Area tiiicrodonta, 

 ('Jiidii.e sp., Callista n. sp. A., D<minia matheuisnnii , Lidn (cf.) iaphria, Phacoides 

 afiifilirieatfix, Madra eaJifornloa^ Nafien oooyarid (?), Saxtdomuji (/ihhosus, Tapes 

 truncata (?), TroeMta costellata, TelUna [Anr/uhis) sp., Tritonlwai sp. , Tlvela 

 inesiana^ and Yoldia n. sp. {aff.) cooperi. On the Searsville road, 2)\ miles west 

 of Stanford University (locality 2), P. andemoul is associated with the following 

 among other species: Agasoiua, gravida, Agasoma kernianum, Dusliila (aff'.) 

 ponderosa, and Pinna alamedensis. At Barker's ranch, Kern County, Mi-. Watts 

 found P. andersoni associated with Agasoma liarl-erianum. and l-ernianum and 

 other supposedh' characteristic lower Miocene forms. /■". and^rsoni occurs with 

 P. era-ssicardo in the upper Miocene 3 miles south of Mount Diablo. In Avenal 

 Canyon, Kern County, P. andersoni is associated with P. andersonl var. harkerianas, 

 Tiirritella ocoyana^ Venus sp., Ostrca sp., and a large flat Dosliila. In the Devils 

 Den country, Kern County, P. andersoni is found with /'. crassicarda in beds of 

 probable lower Miocene (Vaqueros) age. 



The type of P. andersoni, which is now in the collection of the department (^f 

 geology, Stanford University, is from localit}' ]-27, three-fourths mile below Zaj^ante 

 station on Zayante Creek, Santa Cruz County, where it was found associated with 

 P. sespeensis var. hydei and B(danns (ef.) e.sfrei/anus. The l>eds from which the 

 type was taken lie only a few feet below, and conformable with, the base of the 

 characteristic Monterey shales, which are vciv well developed in the vicinity. 



Miocene (upper). Three miles south of ]\Iount Diablo, Contra Costa County 

 (University of California); Pacheco, Contra Costa County (J. P. Smith); San 

 Pablo Bay, near Pinole, Contra Costa County (Merriam, Arnold). 



Miocene (middle and lower). Localit}' 127, Zayante Creek, three-fourths mile below 

 Zaj-antc station; near Glenwood (Miss Hecox); near Magnetic Springs; near 

 Felton (locality 32), Santa Cruz Countj^; near Stanford Universit3^ at localities 

 1, 2, 3, 4, 9, 34, and 3.5, Santa Clara and San Mateo counties (Branner, J. P. 

 Smith, Arnold, and others); Barker ranch, Kern County (Watts); New Almaden 

 (Turner); Contra Co.sta County (Lawson); near head of Slacks Canyon, NE. i 

 sec. 9, T. 22 S., R. 13 E., Mount Diablo meridian. Monterey County (Hamlin); 

 Avenal Canyon, Kern County (Eldridge); Devils Den. Kern County (Eldridge). 



Pectex (Plaijioctenidm) ANDERSONI var. BARKERiANUS 11. var. 



PI. XXVI, (ig. 9. 



Demrijyfion. — Shell averaging about 40 millimeters in altitude, somewhat longer 

 than high, equilateral, somewhat ventricose, and with serrate margins; base regu- 



