Page:American Seashells (1954).djvu/185

Rh $1/2$ to 1 inch in length. Shell thick, with 11 rows of neat, rounded, whitish, evenly spaced beads on the last whorl. Columella grooved; umbilicus a narrow, oblique slit. Color of outer shell ash-gray. Interior dark-tan. Operculum paucispiral. One of the commonest West Indian littoral species, usually found well out of water on the rock cliffs.

$1/2$ to 1 inch in length. Base of shell squarish. Whorls with 2 spiral, carinate rows of sharp nodules in addition to 2 or 3 rows of smaller, blunt nodules. Columella not shelved. Color grayish brown. Operculum multispiral. Lives well above high-tide mark on rocky shores. Be sure not to confuse with Nodilittorina tuberculata whose beads are lined up axially one under the other.

Extremely small shells, conic-ovate; aperture round, peristome complete; whorls moderately rounded. Nuclear whorls smooth. Umbilicus slit-like. There are about 15 confusing species on the west coast of America, most of which are found in Alaskan waters.

4 mm. in length, light-brown, smooth. Suture slightly indented. Uncommon from shore to 15 fathoms.

2 mm. in length, translucent-white, with microscopic spiral striations and fine lines of growth. There are 4 other species in this subgenus which are found in Alaska (C. asser Bartsch, C. kyskensis Bartsch, C. palmeri Dall and C. cerinella Dall).