download pdf

96 American Seashells
Puncturella cucullata Gould Hooded Puncturella
Alaska to La Paz, Mexico.
Figure 30a, b
% to I inch in length, moderately strong. Apex small, elevated and
hooked over toward the anterior end. Behind it is a small, elongate slit pene-
trating through the shell. Internally the slit is separated from the apex by a
calcareous, convex shelf. Exterior with 14 to 23 major ribs and with i to 5
smaller radial ribs between the main ones. The fewer the ribs, the stronger
they are. Shell dull-gray externally, glossy-white inside. The border is cren-
ulated. Found at low tide in Alaska and dredged from 20 to 75 fathoms off
southern California.
Puncturella galeata Gould Helmet Puncturella
Aleutian Islands to Redondo Beach, California.
Figure 30c
% to % inch in length, similar to cucullata, but with an almost smooth
basal edge; with numerous, much finer radial ribs, and with the internal shelf
behind the slit reinforced by a second, straight shelf. Commonly dredged in
mud from 10 to 75 fathoms.
Subfainily DIODORINAE
Genus Diodora Gray 1821
Keyhole Limpets with the internal callus of the hole truncated and fre-
quently minutely excavated behind; shell with its basal margin never raised
at the ends. Central tooth of the radula wide. Compare with Fissurella.
Diadora is a misspelling.
Diodora cayetiensis Lamarck Cayenne Keyhole Limpet
Plate 17m
Virginia to south half of Florida and to Brazil.
I to 2 inches in maximum diameter. Orifice just in front of and slightly
lower than the apex. Many radial ribs with each fourth one larger. Color
variable from whitish, pinkish to dark gray. Interior white or bluish gray.
Just behind the callus of the orifice on the inside there is a deep pit. D. listeri
is much more coarsely sculptured. A common intertidal to moderately deep
water species. It was named by Thomas Say one month after Lamarck's
description as D. alterjiata.
Diodora listeri Orbigny Lister's Keyhole Limpet
South half of Florida and the West Indies.
Plate 17I