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Rh not the common West Florida species usually called “spirata” in other books. See knorri and also fargoi.

For anatomy and relationships in the worm-shells, see the excellent works by J. E, Morton (1951) in the Transactions of the Royal Society of New Zealand.

Differing from spirata in having the early, evenly coiled part pure white in color. The later whorls are very similar to spirata. Common in sponge masses, and frequently washed ashore.

Similar to spirata and knorri, but the "turritella" or wound stage is $3/4$ to 1 inch in length; the shell is thicker and sturdy, its color a drab grayish to yellowish brown. Early whorls tan to brown, with 2 (sometimes 3) spiral cords. Subsequent whorls with 3 major, brown-spotted, thick cords. Aperture with a squarish columella corner. Minute minor threads are between the main cords. Commonly found crawling on mud flats. A race occurs in Texas in which the "turritella" stage is much more slender.

A small worm-like shell with detached whorls throughout. Characterized by the long row of small holes or elongate slits on the middle of the whorl. Early whorls smooth, white; later whorls becoming very spinose and stained with brown. The coiling is very irregular and loose. Grows to about 5 or 6 inches in length. T. modestus Dall may be the young of this species.

These tiny, cucumber-shaped mollusks are occasionally found by screening the beach sand in warm water areas or by shaking out dead sponges. The Caecums begin life in a normal snail-like manner with a tiny, spiral shell, but within a few weeks they grow only in one direction to form a simple, slightly curved tube. The spiral apex is usually knocked off and the hole plugged