Page:American Seashells (1954).djvu/567

Rh ally compressed. Outer surface whitish (opalescent when worn), commonly with numerous, weak, radial, dark lines of periostracum. Interior glossy and with an opalescent sheen. Ossicle inside, under hinge, is opaque-white. Very similar to our figure of the Atlantic hyalijja. Common in sandy mud bot- toms of many California sloughs and bays down to 40 fathoms. Genus Entodesma Philippi 1845 Subgenus Agriodesma Dall 1909 EntodesTfia saxicola Baird Northwest Ugly Clam Plate 29m Alaska to San Pedro, Cahfornia. 2 to 5 inches in length. A very peculiar, ugly and misshapen clam found along the shore burrowing into rocks. Generally oblong in shape, with the posterior end flaring and gaping. Covered with a thick, rough, brown peri- ostracum which partially flakes oflF when dry. Interior brownish tan to whitish with a slight opalescence. Hinge 'ithout teeth, but with a rather large, oblong, whitish ossicle lying under the internally placed ligament. Moderately common from Washington to southwest Alaska. Genus Mytilimeria Conrad 1837 A peculiar, bladder-shaped, very thin shell found embedded in compound ascidians or sea squirts. Mytilhjieria Jiuttalli Conrad Nuttall's Bladder Clam Plate 29q Alaska to Lower California. I to 2 inches in length, obliquely oval, inflated, very fragile, opaque with a thin, brownish periostracum. Beaks small and spiral. No teeth in the weak hinge, but a small, calcareous ossicle is present. Color white with underlayers of slightly pearly material. Common under rocks at low tide to 10 fathoms, always embedded in compound ascidians or sea squirts. Fa7?nly PANDORIDAE Genus Pandora Chemnitz 1795 (Opinion 184) Pandora trilineata Say Say's Pandora Figure 96b Cape Hatteras, N®rth Carolina, to Florida and Texas. % to I inch in length, almost half as high; half-moon-shaped in outline, and with a strong, squarish ridge along the hinge margin which extends pos- teriorly into a fairly long rostrum. Valves very flat, the entire shell very