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MYTILIDAE 35 3
purplish and white. Anterior end has two very tiny purplish teeth. Beyond
the ligament (posterior end) there are 5 to 6 very tiny, equal-sized teeth on
the edge of the shell. Compare with B. citrinus, which is more elongate.
Brachidontes stearnsi Pilsbry and Raymond Stearns' Mussel
Santa Barbara, California, to Oaxaca, Mexico.
/4 to I inch in length, obtusely carinate, with numerous coarse, beaded,
radial ribs which bifurcate. Color brownish purple on the dorsal half, straw-
yellow to brownish yellow on the flattened ventral half. Hinge on dorsal
edge with about a dozen very tiny bar-like teeth. Usually found in colonies
in crevices of stones. Two small clams, Lasaea cistula Keen and L. subviridis
Dall, attach themselves to the byssus of this species. Do not confuse B.
stearjisi with Septifer bifurcams, with which it often lives. B. multijormis
Carpenter and B. adamsianus Dunker are closely related species, if not mere
forms, found in the Panamic province.
Subgenus Ischadiwn Jukes-Brown 1905
Brachidontes recurviis Rafinesque Hooked Mussel
Cape Cod to the West Indies.
Plate 3511
I to 2% inches in length, flattish, rather wide, with numerous wavy
axial ribs. Color outside a dark grayish black, inside a purplish to rosy
brown with a narrow blue-gray border. At the umbonal end there are 3 to
4 extremely small, elongate teeth on the edge of the shell. The anterior end
of the shell is strongly hooked. This s\as known as M. hamatus Say and has
sometimes been placed in the genus Mytilus.
Genus Amygdahnn Megerle von Miihlfeld 181
Shell thin, very smooth, often with colored, cobwebby designs. These
clams build nests for themselves with a copious supply of byssal threads.
Amygdaluni papyria Conrad Paper Mussel
Texas and Maryland to Florida.
1
Plate 28i
I to 1% inches in length, elongate, smooth, glistening, fragile, and
colored a delicate two-tone of bluish green and soft yellowish brown. In-
terior iridescent-white. The ligament is very weak and thin. A. sagittata
Rehder, sometimes dredged off^ Florida and Mississippi, is very shiny, ivory-
white, half of each valve with fine, gray, cobwebby streaks. The umbo is
reinforced inside by a very small, smooth column or rib.