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376 the margins of the valves. Differing from subequilatera in being more ellip- tical in side view, in having the beaks near the middle, with weaker con- centric ribs, and with the inner surface of the valve margins smooth. A com- mon shallow-water species. Astarte subequilatera Sowerby Lentil Astarte Plate 28-0 Arctic Seas to off Florida. I to I /4 inches in length, ovate, moderately compressed. External liga- ment small. Concentric ridges strong, rounded, evenly spaced. Internal mar- gin of valves finely crenulate. Beaks turned slightly forward, often eroded. Color dull light- to dark-brown. Found in shallow water in the north and below 50 fathoms in the south. Common. Compare with bore alls. Astarte undata Gould Waved Astarte Plate 28r New Brunswick to Maine. Similar to subequilatera, but less elliptical, with its beaks near the center and with fewer and stronger concentric ridges. Probably the commonest Astarte in New England. Astarte castaiiea Say Smooth Astarte Plate 28s Nova Scotia to Cape Cod. I inch in length, as high, trigonal in shape, quite compressed. Beaks pointed and hooked anteriorly; external ligament small. Shell almost smooth, except for weak, low concentric lines. Color a glossy light-brown. Inner margin of valves finely crenulate. A commonly dredged species. Astarte nana Dall Southern Dwarf Astarte North Carolina to Florida and the Gulf States. /4 inch in length, slightly trigonal in shape, compressed. With or with- out about 25 well-developed, evenly spaced, rounded, concentric ridges. Ventral and inner edge of valves usually with 40 to 50 distinct small pits or crenulations. Shell cream, tan, brown or rose-brown in color with the beaks usually whitish. A very abundant species dredged in moderately shallow water, especially off eastern Florida. Family CRASS AT ELLIDAE Genus Eucrassatella Iredale 1924 Shell large, thick, equivalve, posteriorly rostrate; ligament and resilium