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318 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 Figure 66d Japan and Alaska to California. 6 to 1 2 inches in length, oblong and flattened. The large, white, butter-