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Rh end smaller than the elliptical posterior end. Shell chalky, dirty-white and with a coarse, varnish-like, yellowish brown periostracum. Worn shells have coarse, concentric, wide growth lines. The pallial sinus is larger in this spe- cies than in solidissima. Moderately common from low-tide line to 60 fath- oms. The form alaskana Dall is probably a synonym. The fossil, 5. voyi Gabb 1868 from the Miocene or Pliocene is possibly only a subspecies. Spisula falcata Gould Hooked Surf Clam Puget Sound, Washington, to California. 2 to 3 inches in length, rather elongate at the narrower anterior end. Exterior chalky with a partially worn-off, light-brown, shiny periostracum. Anterior upper margin of shell slightly concave. Moderately common in sand below low-water line.

Figure 90. Pacific Surf Clams, a, Spisnla dolabriformis Conrad, 3 inches; b, S. hemphilli Dall, 6 inches; e, Spistda catiUiformis Conrad, 4 inches; d, Mactra calif omica Conrad, i ^ inches; e, S. pla?mlata Conrad, 2 inches.