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434 Anicriatn Seashells
Aiacoma incongnm von Martens (fig. 88b) (Alaska to Washington) is
similar, but more oval, with a more pointed slope at the beaks, a straighter
posterior dorsal edge. Its upper pallial sinus line, after nearly reaching the
anterior muscle scar, turns downward and then runs anteriorly before con-
necting with the paUial sinus. Common in Alaska.
Genus Apoly metis Salisbury 1929
Apolymetis intastriata Say Atlantic Grooved Macoma
South half of Florida and the Caribbean.
Plate 32y
2 to 3 inches in length, elliptical, fairly thin but strong and all white in
color. The shell is strongly twisted. At the posterior end, the right valve
bears a strong, radial rib, while on the left valve there is a fairly strong, radial
groove. Pallial sinus very large. Living specimens are not commonly col-
lected, although shells are commonly washed ashore.
Apolymetis biajigiilata Carpenter Pacific Grooved Macoma
Santa Barbara, California, to Ensenada, Mexico.
2 to 3 V2 inches in length, oval, moderately compressed, strong, and dull
grayish white in color. Interior glossy-white with the central portion blushed
with pastel-peach. Left valve with a shallow, radial groove near the posterior
end. Right valve with a corresponding ridge at the end of which the margin
of the shell is shallowly notched. Alias A. alta Conrad. Common.
Family SEMELIDAE
Genus Semele Schumacher 18 17
Resilium supported in a horizontal, chondrophore-like depression which
is internal and parallel with the hinge line. 2 cardinal teeth in each valve.
Right valve with 2 distinct lateral teeth, but practically absent in the left
valve. The ligament is external.
Semele proficua Pulteney White Atlantic Semele
North Carolina to south half of Florida and the West Indies.
Plate 40g
/4 to 1/4 inches in length, almost round, beaks almost central. Lunule
small and pushed in. Fine concentric lines and microscopic radial striations.
Externally whitish to yellowish white. Interior glossy, commonly yellowish,
rarely speckled a little with purple or pink. Moderately common in shallow
water. The color form radiata Say, has a few indistinct radial rays of pink
(pl.400.