TAXONOMY AND BIOSTRATIGRAPHY OF CONIACIAN THROUGH MAASTRICHTIAN ANCHURA (GASTROPODA, APORRHAIIDAE) OF THE NORTH-AMERICAN PACIFIC SLOPE

North American Pacific Slope deposits of Coniacian to Maastrichtian ag e have yielded eight biostratigraphically useful species of Anchura: A . (Helicaulax?) popenoei new species, Coniacian; A. halberdopsis new s pecies, early Campanian; A. callosa Whiteaves, 1903, early Campanian; A. falciformis (Gabb, 1864), late early to middle Campanian; A. phaba new species, middle to late Campanian; A. ainikta new species, middle to late Campanian; A. gibbera Webster, 1983, late Campanian to early M aastrichtian; A. baptos new species, late Maastrichtian to early Dania n. In addition, two other possible species are A. nanaimoensis (Whitea ves, 1879), middle to late Campanian, and Anchura?new species, late Ma astrichtian. These species together with two additional Turonian speci es, A. (Helicaulax) tricosa Saul and Popenoe, 1993, and A. (H.) condon iana Anderson, 1902, allow the definition at least eight Late Cretaceo us Anchura zones for the Pacific Slope. These zones have durations of 1.5 m.y. to 4 m.y. Anchura (H.?) popenoei from northern California app ears most closely related to A. (Helicaulax) tricosa Saul and Popenoe, 1993, of Turonian age from southern California. Anchura callosa, A. f alciformis, A. nanaimoensis, and A. phaba appear to be closely related based on sculptural elements, as does A. gibbera despite having an an terior spur on the wing. However, these species appear to belong to tw o latitudinally differentiated faunal provinces. Species having a nort hern range include A. callosa, A. falciformis, and A. nanaimoensis, wh ereas A. phaba and A. gibbera are from more southern deposits, as are also A. halberdopsis, A. ainikta, and A. baptos.