Mercenaria kennicottii: Shell cuneiform, dark ferruginous brown, ornamented with fine concentric, slightly elevated lamellae. Valves rather inflated, thick ; umbones prominent, rounded ; within the anterior third; anterior end rounded from below to the lunule, which is broad, cordiform and impressed, bounded by a deeply incised line. Extreme anterior end of the valves rather pinched together. Anterior ventral margin arcuated. Posterior end thick, rather produced and pointed. Posterior dorsal side roundly arched from the umbones to the end ; two obsolete carinas pass from the umbones on each side posteriorly, the inner pair forming the boundary of the ligamentary area. Inner posterior and ventral margin finely crenulated. Hinge line strongly arched behind. Dental area broad, teeth strong. Posterior dental process rugose. Muscular impressions large ; pallial sinus short, sharply angulated. Sculpture of fine concentric lamellae, slightly elevated, more so on the anterior end ; more distant on the umbones, thickly crowded near the margin especially anteriorly. Lines of growth prominent at intervals. Lamellae passing over the ligamentary area and lunule. Interior white ; the dark brown of the exterior may be a stain but looks natural. Lon. 2,64. Alt. 2,1. Diameter 1,56 inch. Angle of the pallial sinus 45°. Lon. of do. 0,44 in. Habitat— Neah Bay, W. T., Capt. E. E. Smith.