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MACTRIDAE 449
Genus Miilinia Gray 1837
Miilinia lateralis Say Dwarf Surf Clam
Maine to north Florida and to Texas.
Plate 32-0
% to V2 inch in length, resembling a young Spisula or Mactra, moder-
ately obese, beaks quite prominent and near the center of the shell and point-
ing to\A'ard each other. Exterior whitish to cream and smoothish, except for
a fairly distinct, radial ridge near the posterior end. Concentric lines plainly
seen in the thin, yellowish periostracum. Distinguished from young Spisula
solidissima which have a proportionately much larger chondrophore in the
hinge and which have tiny, saw-tooth denticles on the lower anterior and
lateral hinge-teeth. A very abundant species in warm, shallow water in sand.
Genus Labiosa iMoller 1832
Posterior slightly gaping. Shell fragile. Hinge with a prominent chondrophore.
Cardinal teeth small and close to the chondrophore. Ligament
submerged, except at the anterior end, and separated from the chondrophore
by a shelly plate. Raeta Gray 1853 is the same. This is also Anatina Schumacher
181 7, not Bosc 18 16.
Labiosa plicatella Lamarck Channeled Duck Clam
North Carolina to Florida, Texas and the West Indies.
Plate 32q
2 to 3 inches in length, Y:, as high, egg-shell thin, but moderately strong.
Concentric sculpture of smoothish, distinct ribs which on the inside of the
valves show as grooves. Radial sculpture of very fine, crinkly threads. Color
pure white. Formerly known as Raeta canaliciilata Say. R. cainpechejisis
Gray is also a synonym. Commonly washed ashore, especially along the
strands of the Carolinas, but rarely seen alive.
Labiosa lineata Say Smooth Duck Clam
North Carolina to the north % of Florida and to Texas.
2 to 3 inches in length, % as high, fairly thin but strong. White to tan
in color. Moderately smooth, except for irregular growth lines and tiny, but
distinct, concentric ribs near the beaks. Posterior end with a distinct radial
rib behind which the shell gapes with flaring edges. Uncommon in most
areas of its range.