376 America?! Seashelh 



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 



