Page:American Seashells (1954).djvu/240

190 Lunatia pallida Broderip and Sowerby Pale Northern Moon-shell Figure 43c Arctic Seas to off North Carolina. Arctic Seas to California. 1% to 1% inches in length, not quite so wide, smooth, pure-white in color, and covered with a thin, yellowish white periostracum. Parietal wall moderately thickened with a white glaze. Umbilicus almost closed to slischtlv open. Commonly dredged offshore in cold northern waters. In the Atlantic, this species rarely exceeds i inch in length. P. groenlandica Moller may be this species. Subfamily SININAE Genus Sinum Roding 1798 Sinum perspectivum Say Common Baby's Ear Plate 22s Virginia to Florida and the Gulf States. The West Indies. I to 2 inches in maximum diameter, but very flat, with very large white aperture and strongly curved columella. Numerous fine spiral lines on top of whorls. Color dull-white with a light-brown, thin periostracum. Animal envelops the shell. Commonly found in shallow, sandy areas, especially in the Carolinas and the west coast of Florida. Sinum maculatum Say Maculated Baby's Ear Carolinas and west coast of Florida. Similar to perspectivum, but shell not so flat, with weaker spiral sculp- ture, and colored dull-brown or with yellowish brown maculations. Sinum scopulosum Conrad Western Baby's Ear Monterey to Todos Santos Bay, Lower California. I to 1/4 inches in length, 4 whorls, the early ones being very smooth, the last whorl very large. Numerous spiral grooves can be seen with the naked eye. Shell chalky-white, but usually covered with a thin, yellowish, translucent periostracum. The spire is more elevated and the whorls more inflated than those in S. debile Gould, from Catalina Island to the Gulf of California. S. scopulosum is moderately common, and is the same as S. cali- fornicum Oldroyd.