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352 American Seashelh
has a strongly curved beak, tiny teeth at the umbo, and is a soHd rosy-brown
on the inside. Mytilus plicatuhis Lamarck is this species.
The subspecies deriiissus granosissiimis Sowerby (both sides of Florida to
Texas and Yucatan) is very similar but with almost twice as many ribs which
are finely and neatly beaded. Common.
Modiolus forjjicatus Carpenter California Horse Mussel
Monterey to San Pedro, California.
Plate 29-0
About I inch in length, smoothish, inflated, light-brown periostracum
which wears white at the beak end. Beaks curved strongly forward. Inte-
rior dull white. Found in moderately deep water, and rarely cast ashore.
Associated with Haliotis rufescens.
/Modiolus capax Conrad Capax Horse Mussel
Santa Cruz, California, to Peru.
2 to 6 inches in size. Periostracum thick, often with coarse hairs,
chestnut-brown in color. Worn shell brick-red with bluish mottlings. In-
terior half white, half (ventral) brownish purple. Resembles figure of
Modiolus americanus (PI. 35I).
Genus Brachidontes Swainson 1840
Subgenus Brachidontes s. str.
Brachidontes citriniis Roding Yellow Mussel
Southern Florida and West Indies.
Plate 35!
I /