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CRYPTOPLACIDAE 317
center of each valve. Girdle may have widely scattered tufts of hair. In-
terior of valves white. Common from 5 to 30 fathoms.
S. pallasi Middendorff (Concealed Pacific Chiton) is very similar to
vestitus, but the girdle is much thicker and the bunches of reddish hairs
more numerous. Uncommon from 3 to 10 fathoms.
Figure 66. Pacific Coast chitons, a, Placiphorella velata Pilsbry, i to 2 inches
(California); b, Katharina timicata Wood, 2 to 3 inches (Pacific Coast); c, Syjnmetrogephynis
vestitus Brod. and Sby., i to 2 inches (Arctic waters to Massa-
chusetts and Alaska); d, Amicula stelleri Midd., 6 to 12 inches (Pacific Coast),
showing position of the ist and 7th valves only.
Ceratozona rugosa Sowerby
East Florida to the West Indies.
Genus Ceratozona Dall 188:
Rough Girdled Chiton
Figure 67a
I to 2 inches in length, oblong, slightly beaked. Surface commonly
eroded, whitish gray with blue-green to moss-green mottlings on the sides
of the calves. Surface roughly sculptured. Anterior valve with 10 to 11
strong, rugose, radiating ribs. Lateral areas bounded in front and behind
by a large, rugose rib. Central area with low, rough, longitudinal ribs. In-
terior of valves bluish green. Girdle leathery, yellowish brown and with
numerous, yellowish brown clusters of strap-like hairs. Posterior valve
rather small and with 8 to 10 slits. 35 to 36 gill lamellae. The gills extend the
length of the foot, but do not go as far as the posterior end. Very common,
especially in the Greater Antilles.
Cryptoconchiis floridanus Dall
Family CRYPTOPLACIDAE
Genus Cryptoconchus Burrow 1815
Southeast Florida to Puerto Rico.
White-barred Chiton
Figure 67b
Rarely over an inch in length, long and narrow, and characterized by
its thin, black, naked girdle which extends on to the valves except over
the narrow, beaded dorsal area. These exposed bands in the valves make