Page:American Seashells (1954).djvu/307

Rh a much higher spire, stronger axial ribs, and much stronger, more acute, spiral cords. Moderately common from 25 to 265 fathoms. Amphissa bicolor Dall Two-tinted Amphissa Farralon Islands, to San Diego, California. % to % inch in length, similar to versicolor, but thinner-shelled, usually with fewer ribs, glossy-white in color, but covered with a pale-straw peri- ostracum, and without the small teeth inside the outer lip. Dredged com- monly from 40 to 330 fathoms. Favnly BUCCINIDAE Genus Buccinum Linne 1758 Buccinwn undatum Linne Common Northern Buccinum Arctic Seas^to New Jersey. Europe. 2 to 4 inches in length, solid, chalky gray to yellowish with a moderately thick, gray periostracum. Axial ribs 9 to 18 per whorl, low, extending ^ to V2 way down the whorl. Spiral cords small, usually about 5 to 8 between sutures. Outer lip slightly or well sinuate and somewhat flaring. Aperture and parietal wall enamel-white. Anterior canal short. 1V2 nuclear whorls fairly large, smooth and translucent-white. Operculum oval, concentric, chitinous, and light yellow-brown. A very variable shell which sometimes lacks the axial ribs but may have numerous spiral threads. Common just off- shore to several fathoms in cold water. Buccinum tenue Gray Silky Buccinum Plate 24U Arctic Seas to Washington State. Arctic Seas to the Gulf of Maine. 1V2 to 1V2 inches in length; aperture 'V2 the length of the shell. Outer lip slightly sinuate, thin and slightly flaring. Axial ribs small, numerous, inter- twining and extending from suture to suture. Spiral sculpture of microscopic, beaded threads giving a silky appearance. Color light-brown. Common off- shore. Compare with plectrum Stimpson. Buccinum plectrum Stimpson Plectrum Buccinum Figure 51a Arctic Seas to Puget Sound. Arctic Seas to the Gulf of St. Lawrence. 2 to 3 inches in length; aperture a little more than % the entire length of the shell. Outer lip strongly sinuate, thickened and flaring. Axial ribs