Subgenus (Periploma) C. F. Schumacher, 1817

(3-2-4-0-4-2-0-1-4-0-0-0-0)

affine A. E. Verrill and K. J. Bush, 1898
(3-2-4-0-4-2-0-1-4-1-0-0-0)
Ref. Abbott, 1974 p 561

alaskanum M. W. Williams, 1940
(3-2-4-0-4-2-0-1-4-2-0-0-0)
Ref. Abbott, 1974 p 561

anguliferum (R. A. Philippi, 1847)
(3-2-4-0-4-2-0-1-4-3-0-0-0)
Ref. Abbott, 1974 p 561

argentarium (T. A. Conrad, 1837)
(3-2-4-0-4-2-0-1-4-4-0-0-0)
[=Periploma planiusculum G. B. Sowerby, 1834]
Ref. Abbott, 1974 p 561

discus R. E. C. Stearns, 1899
(3-2-4-0-4-2-0-1-4-5-0-0-0)
Round Spoon Clam
Size 1"-1.5" long
Ref. Abbott, 1974 p 561 d

excurvum (P. P. Carpenter, 1855)
(3-2-4-0-4-2-0-1-4-6-0-0-0)
[=Periploma planiusculum G. B. Sowerby, 1834]
Ref. Abbott, 1974 p 561

fragile (J. G. Totten, 1835)
(3-2-4-0-4-2-0-1-4-7-0-0-0)
Fragile Spoon Clam
Ref. Abbott, 1974 p 560 d

inaequivalvis C. F. Schumacher, 1817 [T]
(3-2-4-0-4-2-0-1-4-8-0-0-0)
[?=Periploma margaritaceum J. B. P. A. Lamarck, 1801]
Ref. Abbott, 1974 p 560

inequale C. B. Adams, 1842
(3-2-4-0-4-2-0-1-4-9-0-0-0)
[=Periploma margaritaceum J. B. P. A. Lamarck, 1801]
Ref. Abbott, 1974 p 560

lenticulare (G. B. Sowerby, 1834)
(3-2-4-0-4-2-0-1-4-10-0-0-0)
[?=Periploma margaritaceum J. B. P. A. Lamarck, 1801]
Ref. Abbott, 1974 p 560

margaritaceum J. B. P. A. Lamarck, 1801
(3-2-4-0-4-2-0-1-4-11-0-0-0)
Unequal Spoon Clam
Size 0.75"-1" long
Syn. ? Periploma inaequivalvis C. F. Schumacher, 1817;
Periploma inequale C. B. Adams, 1842
Ref. Abbott, 1974 p 560 bw

obtusum (S. C. T. Hanley, 1842)
(3-2-4-0-4-2-0-1-4-12-0-0-0)
[?=Periploma margaritaceum J. B. P. A. Lamarck, 1801]
Ref. Abbott, 1974 p 560

papyratium [papyraceum] (T. Say, 1822)
(3-2-4-0-4-2-0-1-4-13-0-0-0)
Paper Spoon Clam
Size 0.5"-1" long
Ref. Abbott, 1974 p 560 bw

planiusculum (G. B. Sowerby, 1834)
(3-2-4-0-4-2-0-1-4-14-0-0-0)
Common Western Spoon Clam
Size 1"-1.75" long
Syn. Periploma argentarium (T. A. Conrad, 1837);
Periploma excurvum (P. P. Carpenter, 1855);
Periploma lenticulare (G. B. Sowerby, 1834);
Periploma obtusum (S. C. T. Hanley, 1842)
Ref. Abbott, 1974 p 561 bw

stearnsii W. H. Dall, 1896
(3-2-4-0-4-2-0-1-4-15-0-0-0)
Ref. Abbott, 1974 p 561

tenerum P. Fischer, 1882
(3-2-4-0-4-2-0-1-4-16-0-0-0)
Ref. Abbott, 1974 p 561

undulatum A. E. Verrill, 1885
(3-2-4-0-4-2-0-1-4-17-0-0-0)
Ref. Abbott, 1974 p 561 d