WESTERN BITTERSWEET Pectunculus septentrionalis Middendorff, 1849: 67; P. kaschewarowi Grewingk, 1850: 352; Axinaca (?septentrionalis) subobsoleta Carpenter, 1864c: 644; 1864d: 425; Glycymeris profunda Dall, 1878: 13; G. grewingki Dall, 1909a: 107; G. conradi Dall, 1909a: 107, non (Whitfield, 1885); G. gabbi Dall, 1909a: 108; G. coalingensis R. Arnold, 1910: 80; G. corteziana Dall, 1916b: 13, nom. nud.; 1916c: 402; G. migueliana Dall, 1916b: 13, nom. nud.; 1916c: 402; G. larvata Hanna, 1924, nom. nov. pro G. conradi Dall, non (Whitfield); G. guadalupensis A. M. Strong, 1938: 213. Shell ovate to trigonal, discoidal, compressed to moderately inflated, moderate to thin in thickness; anterior end generally longer, slightly produced; posterior margin rounded. Beaks orthogyrate. Periostracum thick, dehiscent, finely hirsute. Radial sculpture evident in unworn specimens. Surface chalky, ash-white, often with brown flecks and maculations. Hinge plate arched. Length to 45 mm. Specimens are variable and often eroded. Northern material is large and inflated; in the south, typical specimens are more discoidal and thinner. The hinge is variable, being narrow in some specimens and wider in others. The cardinal area above the hinge also varies in height. Similar to the western Pacific G. (A.) yessoensis (G. B. Sowerby III, 1889), which differs in attaining a larger size, up to 60 mm. This species has sometimes been associated with Glycymeris barbarensis (Conrad, 1857), but reexamination of Conrad's original material proves this species to be a senior synonym of the Paleocene to Eocene G. (Glycymerita) major (Stanton, 1896). Chirikof Island (55.6°N, 155.6°W) [USNM] and Cook Inlet (59.2°N) [LACM], Alaska, to Rocas Alijos, Baja California Sur (25.0°N) [LACM], and off Isla Smith in the Golfo de California (29.1°N) [Skoglund Coll., LACM], from the intertidal zone to 400 m. Recorded as early as the Miocene in western North America.