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344 American Seashelh
Small byssal gape present on the ventral margin. Moderately common. Area
balesi Pilsbry and McLean is this species.
Genus Arcopsis von Koenen 1885
Ligament limited to a very small, triangular, or bar-like area bet^veen
the umbones.
Arcopsis adamsi E. A. Smith Adams' Miniature Ark
Cape Hatteras, North Carolina, to Brazil.
Figure 26b
/4 to % inch in length, oblong in shape, moderately fat, flattened sides;
white to cream in color. Periostracum very thin. Sculpture cancellate. Lig-
ament limited to a very small, triangular, black patch between the umbones.
The muscle scars are usually bordered by a calcareous ridge. Inner margin
of valves smooth. Common under rocks.
Subfamily ANADARINAE
Genus Anadara Gray 1847
Subgenus Larkinia Reinhart 1935
Anadara multicostata Sowerby Many-ribbed Ark
Newport Bay, California, to Panama.
Shell large, 3 to 4 inches in length, very thick and squarish, 31 to 36
radial ribs. The left valve slightly overlaps the right valve. Found in sandy
areas by dredging in depths over 12 feet. A. grandis Broderip and Sowerby
in Mexican and Panamic waters is larger, heavier and has 25 to 27 ribs.
Anadara notabilis Roding Eared Ark
Northern Florida to the Caribbean and Brazil. Bermuda.
Plate 27P
1/4 to 3^ inches in length. 25 to 27 ribs per valve. Fine concentric
threads cross the ribs and are prominent between the ribs. The ribs never
split. Rare in Florida; common in the West Indies.
Formerly called auriculata Lamarck which is from the Red Sea. A.
deshayesi Hanley is a synonym of notabilis.
Anadara lienosa fioridana Conrad Cut-ribbed Ark
North Carolina, Florida to Texas and the Greater Antilles.
Plate 27-0