MIOCENE PECTENS. 



67 



characteristic Miocene fossils, among' which was a large IWten. (prol)al)ly /irojxttnlus 

 Conrad) with medially sulcated ribs on the right valve. 



Miocene. Between Clallam Bay and Pysht River, Clallam County, Wash. (Diller; 

 Arnold); north end of Popotf Island. Alaska (Dali). 



Pecten (Chlamys) hamlini n. sp. 



PI. XI, fig. 2. 



Description. — Type somewhat distorted but originally aliout (id millimeters in 

 altitude, and probal^ly somewhat shorter than high; moderately convex; base 

 evenly rounded; sides nearly straight. Right valve with 4 broad, sipiarish ribs, 

 each ornamented above by about 5 prominent imbricated radiating ridges, and 

 separated by relatively narrow interspaci^s; hinge line more than one-half length 

 of disk; anterior ear much longer than posterior and ornamented by several 

 imbricated radiating ridges; byssal notch quite prominent; posterior ear short and 

 radiallj' ridged. 



Diiiieiisionii. — (Of the distorted type.) Alt. 60 mm.; long. (jSnun.; hinge line 

 40 mm. ; diameter 24 mm. 



This species is closely allied to P. nyttfxi^ but is distinguisiiable from the 

 latter species by its relatively broader {'I) disk and longer hinge line. The char- 

 acteristics of sculpture are approximately the same in the two species. 



The geologic position of P. hamlini is somewiiat uncertain, although i\w 

 meager fauna with which it is associated at the type locality points toward its cor- 

 relation with the Vaqueros or lower Miocene. The type of P. Ii<niiliiii (U.S.N.M. 

 No. 164S44) was collected by Mr. Homer Hamlin near the head of iSlack's Canyon, 

 in the Mount Diablo Kange, Monterey County, where it was associated with 

 P. est rell anus Conrad, Chiom- n. sp. (large, and with coarse sculpture), Chiane 

 (cf.) inatheiosonii Gabb, and 2Ltctra (aff.) catHlifoTnds Conrad. 



A specimen, which is probably a left valve of /'. Itanilini^ was found asso- 

 ciated with Pecten hranneri in the lower Miocene at Tutf Hill, near Stanford 

 University, Santa Clara County. This specimen has three widely separated, nar- 

 row, ridge-like ribs, and the interspaces are ornamented by a number of rather 

 coarse radiating riblets; altitude 31 millimeters. 



Miocene (lower?). Locality 3851, U. S. Nat. Mus. , head of Slacks Canyon, Mount 

 Diablo Range, Monterey County (Hamlin); Stanford University (Tuii' Hill), 

 Sauta Clai-a County (Arnold). 



Pecten (Chlamys) ndtteri n. sp. 



PI. XI, figs. 3, 4, and 4<(. 



Description. — Shell averaging about 6.5 millimeters in altitude, slightly higher 

 than long, inequivalve, equilateral, more or less ventricose, and often showing 



