J70 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



of California. The paper presents a fauna obtained from the Umpqua for- 

 mation and a tentative correlation of the beds containing the fauna with the 

 uppermost Tejon of the California province. 



EVOLUTION OF THE PACIFIC COAST M ACRID JE 

 BY EABt, L. PACKARD 



{Abstract) 



The genus Spisiila, represented in the Horsetown beds by Spisula ashburneri 

 (Gabb) became dominant in the Middle Miocene, thence gradually declining 

 to the present day. The earliest undoubted mactroid species occurs in the 

 Miocene, reaching its greatest development at the present time. The mulinoid 

 forms appeared suddenly in the early ]\Iiocene, spread rapidly, and then 

 quickly disappeared from the region north of Mexico. 



CORRELATION OF THE TERTIARY FORMATIONS IN WESTERN WASHINGTON 



BY CHARLES E. WEAVER 



