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104 American Seashells
I % inch in maximum diameter, elliptical in outline, generally with a low
apex which is placed % back from the front end. The 15 to 25 strong, coarse
radiating ribs give the edge of the shell a strong crenulation. Color dirty
gray-green. Underside of shell whitish, irregularly stained in the center with
blackish brown. Edge of shell between the serrations is stained blackish to
purplish brown. A common species found clinging to rocks high above the
water line but within reach of the ocean spray. A. spectrum Nuttall is the
same species. Do not confuse with the smaller A. conus which is evenly
glossed, instead of coarse and dull, on its interior center.
Acmaea testudinalts scutum Eschscholtz Pacific Plate Limpet
Alaska to Oregon (common) to Lower CaHfornia (rare).
I to 2 inches in maximum diameter, almost round in outline, quite flat,
with the apex toward the center of the shell. Smoothish, except for very fine
radial riblets in young specimens. External color greenish gray with slate-gray
radial bands or mottlings. Interior bluish white with faint or darkish brown
spot. Inner edge with band of alternating bars of black or brown and bluish
white. The name of this species was also known as tessulata Miiller. The
typical testudmalis from the Arctic Seas and New England rarely, if ever,
exceeds a size of i K- inches, is not so round, and has a darker, more con-
centrated brown patch on the inside. Intergrades exist in Alaskan waters.
The Pacific race was also named patina Esch.
Acmaea asfin Middendorff Black Limpet
Alaska to Mexico, clinging to the gastropod, Tegula.
/4 inch in maximum diameter, high-conic, elliptical in outline, and solid
black inside and out. In the northern part of its range, the Black Limpet is
found living attached to the common snail, Tegula funebralis A. Adams,
Acmaea triangularis Carpenter Triangular Limpet
Southern California to Gulf of California.
Yi inch in maximum diameter, oblong in outline, side view distinctly
triangular. Color whitish with 3 or 4 vertical, rather broad, brown stripes on
each side. Found among coralline algae from the shore line down to several
fathoms. Uncommon.
Acmaea depicta Hinds Painted Limpet
Santa Barbara, California, to Lower California.