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318 Arnencmi Seashells
it appear as if a streak of white paint had been appHed along the top of the
animal. The side of the girdle at each valve-suture has a minute pore bearing
short bristles, but these 2 features are commonly difficult to see. A variety
is found with a brown-colored girdle. 16 gill lamellae. They begin halfway
back along the side of the foot. Uncommon.
Genus Acanthochitona Gray 1821
Acanthochitona spicnlosa Reeve Glass-haired Chiton
Southeast Florida and the West Indies.
I to I /4 inches in length, elongate, with the girdle covering most of
the valves. There are 4 clumps of long, glassy bristles near the anterior valve
and one on each side of the other valves. The clumps are set in cup-like
collars of the girdle skin. End valves and lateral areas of middle valves cov-
ered with tiny, round, sharply raised pustules. The dorsal, longitudinal
ridge is raised, narrow, distinct and smoothish except for microscopic pin-
points. Lower edge of girdle with a dense fringe of brown or bluish bristles.
3 2 gill lamellae. The gills begin about % back along the side of the foot and
do not extend quite so far back as the posterior mantle margin. A moderately
common species in shallow water. A. astriger Reeve is the same species.
Acanthochitona pygmaea Pilsbry Dwarf Glass-haired Chiton
West Coast of Florida to the West Indies.
^ to % inch in length, moderately elongate and colored cream, green,
brown or variegated with these colors. Similar to A. spicnlosa, but smaller,
and with its dorsal ridge triangular, less elevated and cut by longitudinal
grooves. The pustules on the lateral areas and the end valves are round
or oval. The clumps of bristles are the same. Not uncommonly found
among rocks and dead shells at low tide.
Acanthochitona balesae Pilsbry 1940 from the Lower Keys is very
elongate, only % inch in length; the pustules on the lateral areas are pro-
portionately larger and fewer, and the dorsal ridge is rounded and covered
with small, granulose pustules. Rare at Bonefish Key, Florida.
Genus Amiciila Gray 1842
(Cryptochiton Middendorff 1847)
Amicula stelleri Middendorff Giant Pacific Chiton
Japan and Alaska to California.
Figure 66d
6 to 1 2 inches in length, oblong and flattened. The large, white, butter-