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ARCIDAE 345
2/4 to 5 inches in length, elongate. Ribs 30 to 38 in number, square,
faintly divided by a fine-cut line. Fine, raised, concentric lines seen between
weakly beaded ribs. Left valve very slightly larger than right valve. Periostracum
light- to dark-brown. Not very common.
Typical lienosa Say is fossil and very close in characters to floridana.
This species has often been called A. secticostata Reeve which is not so
elongate and whose origin is unknown.
Anadara baiighvimii Hertlein Baughman's Ark
Off the Texas Coast.
1% inches in length, similar to A. lienosa fioridmia, but much fatter,
with 28 to 30 weakly noduled ribs which are not split, and with a strongly
posterior-sloping anterior ventral margin. Common offshore down to 50
fathoms. A. springeri Rehder and Abbott, published a month later, is this
species.
Anadara transversa Say Transverse Ark
South of Cape Cod to Florida and Texas.
Plate 27s
% to 1/4 inches in lengtli. Left valve overlaps right valve. Ligament
fairly long, moderately narrow, rough or pustulose. Ribs on left valve usually
beaded, rarely so on right valve; 30 to 35 ribs per valve. Periostracum gray-
ish brown, usually wears off except along base of valves. Fairly common in
mud below low water. The smallest of the Atlantic Anadaras. Distinguished
from ovalis by its longer, wider, more distinct external ligament. A. sulcosa
van Hyning 1 946 is this species.
the same.
Subgenus Lunarca Grav 1847
The subgenera Argina Gray and Arginarca McLean 1951 are probably
Anadara ovalis Bruguiere Blood Ark
Cape Cod to the West Indies and the Gulf States.
Plate 27t
1/4 to 2% inches in length, not very thick, roundish to ovate; square,
smooth ribs; ligament very narrow and depressed; beaks close together. Peri-
ostracum black-brown, hairy. Ribs 26 to 35
in number.
Dall considered the forms ''pexata Say" and ''americana Wood" too in-
distinct for recognition. This species was known for a long time as campechiensis
Gmelin and is common.