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CALYPTRAEIDAE 171
Variable in shape, rarely quite flat, sometimes high and arched. They may
be corrugated if the individual has lived attached to a scallop or ribbed
mussel. A common littoral species. When collecting on the west coast of
Florida, do not confuse with C. maculosa. C. fornicata has been introduced
to the West Coast of the United States.
Crepidula maculosa Conrad Spotted Slipper-shell
AVest Coast of Florida to Vera Cruz, Mexico.
Resembling C. fornicata, but often spotted with small, mauve-brown
blotches and sometimes streaked. The edge of the deck is straight or only
very slightly convex. There is an oval muscle scar on the inside of the shell
just below and in front of the right anterior edge of the deck and the main
shell. The young are very much like southern forms of C. convexa Say.
Crepidula convexa Say Convex Slipper-shell
Massachusetts to Florida, Texas and the West Indies.
Plate 2 in
^ to ^ inch in size, usually highly arched and colored a dark reddish to
purplish brown. Interior, including the deck, chestnut to bluish brown.
Some specimens may be spotted. The edge of the deck is almost straight.
There is a small muscle scar inside the main shell on the right side just under
the outer corner of the deck (see also maculosa). Some specimens are thick
and heavy, others quite fragile, the latter type found attached to other shells.
Common just offshore down to 1 16 fathoms.
The form glauca Say is H inch long, thin-shelled, usually dark-brown
or translucent-tan, and with a white deck. It is found in over-crowded col-
onies on eel-grass where specimens become long and narrow. C. acuta Lea
is this form also.
Crepidula aculeata Gmelin Spiny Slipper-shell
North Carolina to Florida, Texas and the West Indies.
Plate 2iq
/4 to I inch in size, similar to foniicata, but characterized by its rough,
spinose exterior, thinner and flatter shell and by its irregular edges. Color
whitish, although often heavily mottled with reddish brown. The exterior
is sometimes stained green by algal growths. A common species found at-
tached to stones, mangroves and other shells. Occasionally dredged.
Crepidula onyx Sowerby Onyx Slipper-shell
Monterey, California, to Peru.
Plate 2of