Page:American Seashells (1954).djvu/204

Cerithium muscarum Say Fly-specked Cerith Plate 19m South half of Florida and the West Indies. I inch in length, moderately elongate. Siphonal canal rather long and twisted to the left. 9 to 1 1 nodulated axial ribs on each whorl. Base of shell with a very strong spiral cord, often nodulated. Former varices rarely pres- ent. Apertural side of body whorl convex. Color slate- to brown-gray, usually with brown to reddish specks in spiral rows. Common in shallow, warm waters on the west coast of Florida. Cerithium literatiim Born Stocky Cerith Plate 19I Southeast Florida, Bermuda and the West Indies. I inch in length, half as wide; siphonal canal short. Aperture side of body whorl slightly flattened. Usually i weak, former varix present. With numerous coarse spiral threads, and with a spiral row of 9 to 12 sharp, promi- nent nodules just below the suture. Sometimes a second, smaller row of spines is on the periphery. Color whitish with spiral rows of many black or reddish squares. Common in shallow water on the Lower Florida Keys. Cerithium ebiirneum Bruguiere Ivory Cerith Plate i9q Southeast Florida, the Bahamas and Greater Antilles. % to I (rarely iK>) inches in length, variable in shape, but usually moderately elongate. Each whorl has 4 to 6 spiral rows of from 1 8 to 2 2 small rounded beads. The beads are slightly larger in the middle row. There are usually a number of fairly large, former varices. Color variable: all white or cream, or with reddish brown blotches. Very common in shallow water. C. versicolor C. B. Adams is this species. Compare with algicola which may ultimately prove to be a genetic form of this species. Cerithiwn algicola C. B. Adams Middle-spined Cerith Plate I9P Southern third of Florida and the West Indies. I inch in length, similar to eburneum, but characterized by each whorl having the middle spiral row of 9 to 12 beads fairly large and pointed. These large beads may be axially drawn out to form low ribs. Former varices are not often present. Color as in ehumewn. Common in the West Indies. C. liter atum has its strongest row of spine-like beads just below the suture. Certthiu7n variabile C. B. Adams Dwarf Cerith Plate 19-0 South half of Florida to Texas and the West Indies.