Page:American Seashells (1954).djvu/193

Rh heavily beaded, spiral cord. Operculum, corneous, thin, paucispiral, brown and with lamellate growth lines. Moderately common in sand below low-water line. Known for years as A. granulata Lamarck which, however, is a later name.

$1/2$ inch in diameter, similar to A. nobilis, but glossy-smooth on top except for two microscopic spiral threads above the suture, with a smooth rounded base and with its deep umbilicus bordered by 2 beaded spiral rows, the innermost having about 30 bar-like beads (in contrast to 12 in nobilis). Operculum chitinous, brown and multispiral. Uncommon from 16 to 63 fathoms. Provisionally placed in this genus.

$3/4$ inch in diameter, similar to nobilis, but smaller, with the spire much flatter, whorls almost smooth, periphery very sharp, and without color spots. Rare in 45 to 73 fathoms.

Lives in closely packed colonies of long, worm-like shells about 2 to 4 inches in length; each tube is about $1/8$ inch in diameter. Shells rarely coiled, except at the beginning. Moderately fragile, gray to rusty-brown in color, and weakly sculptured spirally and longitudinally. Colonies of this species frequently form large reefs or banks.

Similar to nigricans, but greatly coiled, and with heavier, larger shells which are strongly rugose. Occurs in compact masses attached to rocks and other shells. Color dark brownish. P. erectus Dall is smoother, pure white in color, and with the last part of the tube sticking straight up from the