Fig. 10. Thyasirid bivalve Conchocele cf. bathyaulax Hickman, 2015. A. ZPAL L.16/7 from an upper Oligocene seep carbonate of the Pysht Formation, East Twin River, northwestern Washington State, USA; an articulated specimen in left (A1) and right (A2) views, showing characteristic rhomboidal shape with roughly parallel, convex dorsal and ventral margins, and roughly parallel anterior and posterior margins, asterisk shows a lateral aspect of a secondary ridge (A1); anterior view (A3), showing anterior pedal and adductor muscle scars, weakly incurved umbones and inflated shells, asterisk shows a frontal aspect of a secondary ridge shown in A1; dorsal view (A4), shows moderately deep posterior sulcus. B. ZPAL L.16/8 from an upper Eocene–lower Oligocene of the Canyon River, Lincoln Creek Formation, western Washington State, USA; a medium-sized specimen in left lateral view, showing incurved umbo. C. ZPAL L.16/9 from an upper Oligocene of the Pysht Formation, East Twin River, northwestern Washington State, USA; a large specimen in left (C1) and right (C2) lateral views with umbo more protruding than ZPAL L.16/7, 8 (A, B), asterisk shows a lateral aspect of a secondary ridge shown in C3; anterior view (C3) showing weak secondary ridge running from umbo towards the anteroventral angle (asterisked).