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DENTALIIDAE 331
Subgenus Graptacme Pilsbry and Sharp 1897
Dentalimn eboreum Conrad Ivory Tusk
North CaroHna to both sides of Florida and the West Indies.
Figure 696
I to 2^ inches in length, glossy, ivory-white to pinkish. Apical slit
deep, narrow and on the convex side. Apical end with about 20 very fine
longitudinal scratches. Common in sandy, shallow areas.
Dentalium semistriolatum Guilding Half-scratched Tusk
South Florida and the West Indies.
About I inch in length. Similar to eboreum, but curved more, with
apical slits on the side, and its color translucent-white with milky patches.
Some specimens may be reddish near the apical end. Common from i to 90
fathoms.
Dentalium calamus Dall Reed Tusk
North Carolina to east Florida and the Greater Antilles.
% to I inch in length, almost straight and glassy-white. Most of the
shell has minute, longitudinal scratches (about 16 per mm.). The apical end
is sealed over by a bulbous cap which bears a small slit. Uncommon.
Subgenus Episiphon Pilsbry and Sharp 1897
Shells very small, needle-like, wholly lacking longitudinal sculpture and,
as in some other •subgenera, having a projecting, thin tube at the posterior
end after the tip is broken or lost. Only one species in the Western Atlantic.
Dentalium sowerbyi Guilding Sowerby's Tusk
North Carolina and Texas to Florida and the Lesser Antilles.
10 to 15 mm. in length. Needle-like, not fragile, curved, glossy-white.
Crowded rings of growth microscopic on tip. Apex without slit and from it
projects a very thin inner tube. Erroneously known previously as D. filum
Sowerby. Commonly dredged from 17 to 180 fathoms.