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102 American Seashells
Subgenus Collisella Dall 1871
Pacific Coast Species
Acmaea pelta Eschscholtz Shield Limpet
Alaska to Lower California.
Plate i8n
I to I % inches in maximum diameter, elliptical in outline, with a mod-
erately high apex which is placed Vs to almost % way back from the anterior
end. With about 25 axial, weakly developed, radial ribs. Edge of shell slightly
wavy. External color of strong black radial, often intertwining, stripes on a
whitish cream background. Interior usually faint bluish white, with or with-
out a dark-brown spot. Inner border edged with alternating black and cream
bars. A common rock-dweller.
Acmaea fenestrata Reeve Fenestrate Limpet
Alaska to Lower California.
Plate i8t
I to I /4 inches in maximum diameter, almost round in outline, rather
high, and smoothish. The northern subspecies, cribraria Gould (pi. i8w),
found from Alaska to northern California, has interior with various shades of
glossy, chocolate-brown, and with a narrow, solid black border. The exterior
is plain dark-gray. The typical southern fenestrata Reeve (pi. i8t), found
from Point Conception south, has an external color pattern of regular dottings
of cream on a gray-green background. Its interior has a small, brown
apical spot surrounded by a bluish area and bordered at the margin of the
shell with brown. Intergrades occur near Point Conception. This species is
the only Pacific Acmaea which lives among loose boulders that are set in sand.
It only feeds when submerged. Common.
Ac7naea conus Test Test's Limpet
Point Conception, Cahfornia, to Lower California.
Plate i8g
% inch in maximum diameter. Shell low, and like A. scabra, is with
distinct but widely spaced, radial ribs. Distinguished from scabra by its
glossy, smooth interior which often has an evenly colored brown center.
A. scabra has a rough interior center and the brown stain looks smeared.
However, this species may be a form of scabra. It is very abundant south of
La Jolla and is found with A. scabra and A. digitalis.
Acmaea limatula Carpenter File Limpet
Puget Sound to Lower California.
Plate 18-0