P r. A 1^ E XVII. 



MIOCENE PECTENS. 



[Unless otherwise stated all tigitres are appniximati'ly natural size.] 



Page. 



Fig. 1. Pecten { Lyropedcn) rranskvrdo Ciinr;iil. l'. { ' 71 



Exterior of slightly imperfect riiilit valve: altitude 97 mm. San Palilo fnrmation (upper 



Miocene), Contra Costa County. Cal. (:\I. B. ) 



Fu;. le. Same specimen as fig. 1 71 



Exterior of imperfect left valve. (M. B.) 



Fic;. \h. Same specimen as fig. 1 71 



View of both valves from the rear, showing constriction <>f ilisk. (S.) 



178 



