Subgenus (Hemimactra) W. Swainson, 1840

(3-4-4-0-21-3-2-92-2-0-0-0-0)
Ref. Abbott, 1974 p 489
Lindner, 1977 p 111
Vaught, 1989 p 130
[see also as Genus]

polynyma (W. Stimpson, 1860)
(3-4-4-0-21-3-2-92-2-1-0-0-0)
Stimpson's Mactra
Ref. Abbott & Dance, 1982 p 335 c

alaskana W. H. Dall, 1894
(3-4-4-0-21-3-2-92-2-1-1-0-0)
[=Mactromeris polynyma (W. Stimpson, 1860)]
Ref. Bernard, 1983 p 40

solidissima (L. W. Dillwyn, 1817) [T]
(3-4-4-0-21-3-2-92-2-2-0-0-0)
Atlantic Surf Clam, Atlantic Surfclam
Ref. Abbott, 1974 p 489 bw
Abbott & Dance, 1982 p 335 c
Amer. Fish. Soc., 1988 p 40

similis (T. Say, 1822)
(3-4-4-0-21-3-2-92-2-2-1-0-0)
Ref. Abbott & Dance, 1982 p 335
Syn. Spisula raveneli (T. A. Conrad, 1831)
Ref. Abbott, 1974 p 489

solidissima (L. W. Dillwyn, 1817)
(3-4-4-0-21-3-2-92-2-2-2-0-0)