Cretaceous and early Tertiary Pholadidae (Mollusca: Bivalvia) from the
Pacific Slope of North America are rare and only poorly known. Three
new species, each the earliest known Pacific Slope representative of i
ts respective genus, are described: Barnea (Anchomasa) saulae n. sp. (
Pholadinae) from the Upper Cretaceous (Coniacian and Santonian) Reddin
g Formation near Redding, uppermost Sacramento Valley, Shasta County,
northern California; Chaceiafulcherae n. sp. (Martesiinae) from three
widely separated areas of outcrop represented by 1) the middle Miocene
(''Temblor'') Temblor Formation near Oil City and in Jasper Canyon, w
estern Fresno County, central California, 2) the middle Miocene (''Tem
blor'') Topanga(?) Group in the northern Santa Ana Mountains, Orange C
ounty, southern California, and 3) the upper Miocene (Wishkahan) Monte
sano Formation on the Middle Fork of the Satsop River, Mason County, w
estern Washington: and Netastoma squiresi n. sp. (Jouannetiinae) from
the lowest Eocene (uppermost ''Meganos'') part of the Santa Susana For
mation north of Simi Valley in the Santa Susana Mountains, Ventura Cou
nty, southern California.