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420 close together. Posterior end with wavy ribs consisting of fine mud particles laid down over the shell by the animal. There is an enclosed, elongate fur- row between the beaks and the hinge. Color yellowish white. Found in burrow holes in coral rocks. Not uncommon. Subgenus Fetricolaria Stoliczka 1870 Fetricola pholadiformis Lamarck False Angel Wing Plate 32Z; figure 94b Gulf of St. Lawrence to the Gulf of Mexico and south, 2 inches in length, elongate, rather fragile and chalky-white. With numerous radial ribs. The anterior 10 or so are larger and bear prominent scales. Ligament external, located just posterior to the beaks. Cardinal teeth quite long and pointed. The siphons are translucent-gray, large, tubular and separated from each other almost to their bases. A very common clay and peat-moss borrower. Genus Rupellaria Fleuriau 1802 Rupellaria typica Jonas Atlantic Rupellaria Plate 306 North Carolina to the south half of Florida and the West Indies. About I inch in length, oblong, flattened anteriorly; compressed, usually attenuated and gaping posteriorly. Beaks point anteriorly. Exterior gray or whitish and with numerous, irregularly spaced, coarse radial ribs. Interior uneven and brownish gray. This coral borer is variable in shape and uneven in texture. It may also be truncate at the posterior end. Moderately common. Rupellaria tellimyalis Carpenter West Coast Rupellaria Plate 3 It Santa Monica, California, to Mazatlan, Mexico. I to I % inches in length. Oblong-elongate, variable in shape and out- line due to crowding in the rock burrow. Shell fairly thick, white, except for purplish blotches commonly behind the hinge and at the posterior end. Radial threads are coarser at the anterior end. Growth lines are irregular and coarse. Pallial sinus broadly rounded at its anterior end. Early or nep- ionic shell is shaped somewhat like a Donax, smooth, translucent purplish brown and rarely found attached at this early stage to rocks and kelp stalks. R. calif orniensis Pilsbry and Lowe is identical. Rupellaria dejiticulata Sowerby known only from Peru has a similar nepionic shell (contrary to other reports), has a narrower, triangular pallial sinus, and (contrary to reports) is a more fragile shell. Its anterior end is