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452 American Seashells
Genus Ervilia Turton 1822
Shell small, concentrically striate, and sometimes brightly hued. Liga-
ment absent; resihum small and internal. Laterals small. Left cardinal large
and bifid or split.
Ervilia concentrica Gould Concentric Ervilia
North Carolina to both sides of Florida and the West Indies.
%6 of an inch in length, % as high, elliptical in outline, moderately com-
pressed, although some are somewhat inflated. Each end is rounded to the
same degree, and the beaks are central. There is a pinpoint depression just
behind the glossy, inroUed beaks. Sculpture of fine, numerous concentric
ridges. Radial threads may be present to form tiny beads. Color white,
yellow or commonly with a pink blush. Common just offshore to 50 fathoms.
E. rostratula Rehder from Lake Worth, Florida, is similar, but the posterior
end is slightly more pointed.
Family HIATELLIDAE
Genus Hiatella Daudin 1801
Shell irregular due to nestling and burrowing habits. Texture chalky.
No definite teeth in the thickened hinge of the adults. Pallial line discon-
tinuous; siphons naked and slightly separated at the tips. Saxicava Fleuriau
1802 is the same.
Hiatella arctica Linne Arctic Saxicave
Figure 92a
Arctic Seas to deep water in the West Indies. Arctic Seas to deep water
off Panama.
PKODISSOCONCH
Figure 92. The young shells of Hiatella reared under the same artificial conditions.
a, Hiatella arctica Linne; b, H. striata Fleuriau. (After M. Lebour 1938.)
Generally i inch in length, but rarely 2 to 3 inches. A very variable
species in its shape. The young are rather evenly oblong, but the adults
become oblong, oval or twisted and misshapen. The shell is elongate with