The Round-Mouthed Snails - Family Cyclostomidae

THE ROUND-MOUTHED SNAILS - FAMILY CYCLOSTOMIDAE. Shell spiral, often depressed, not much elongated; mouth round, lip simple; operculum spiral, circular; foot long; lingual teeth hooked, recurved, in seven rows; mouth proboscis-like, without jaws; air sac on back of neck, with open mouth; sexes distinct; reproduction oviparous.

A large family of terrestrial, air-breathing snails, resembling the Littorinidx in structure. Chiefly tropical, in the eastern hemisphere.

Genus CYCLOSTOMA, Lam.

Shell cone-shaped to globose, thin; umbilicus wide; oper culum spiral, calcareous, foot divided in middle line, sides move alternately in walking; snout is used too, so locomotion is some what like the looping snail's. A large genus, with range centred in Madagascar.

Cuvier's Cyclostoma

(C. Cuvieranum, Petit.), the giant of the genus, much depressed and thin, is strikingly angled with two sharp keels, separated by a flat plane, and the whole surface is finely striated. The colour is dull, a pale chocolate hue, darker on the keels. The lip flares, and is thickened with an inner rim of white enamel. The pit is wide and deep, all but piercing the apex. These mollusks are representative of a group of species of large size, and handsome form and sculpture. Diameter, 21 inches.

Habitat.—Madagascar.

The Cyclostoma (C. Naticoides, Pfr.) is solid, polished, flesh-pink, with rounded whorls increasing to a swollen body whorl, and a thickened, scarcely flaring lip. An ear-like lobe of callus closes the pit. The shell lining is orange-hued.

Habitat.— Socotra, north of Madagascar.

20(3 The Round-mouthed Snails The Beautiful Cyclostoma (C. pulchra, Gray) has three exquisitely fluted coils that flare into a wide ruffle about the circular aperture. The apex is elevated, the pit deep and wide.

Colour, pale brown, obscurely spotted. This is one of the most beautiful West Indian species. Diameter, 1 inch or more.

Habitat.— Jamaica.

Genus CHONDROPOMA, Pfr.

Shell oblong, turreted, of few rounded whorls, aperture rounded; lip flaring; operculum spiral, flat; nucleus eccentric.

Our American species, C. dentata, Say, is very plain, beside the more highly ornamented Cuban species. It is finely cancellated, yellow with brownish streaks both ways, and the slender spire is usually broken off. The mollusk has a curious habit of spinning a thread by which it hangs suspended from a leaf or other convenient object, with its operculum closed tight. It is very quick of motion, gliding along on its foot, and advancing the shell by a series of jerks. Length, inch.

Habitat.— Southern Florida.

C. Shuttleworthi,

Pfr., is variable in markings, but always brown on a pale ground. The rounded whorls are covered with close spiral stria;, and the lip is bordered with a wavy frill, rayed with brown. Length, 1 inch.

Habitat.— Cuba.

Genus CYCLOTUS, Guilding Shell depressed, turbinated, elegantly convoluted, broadly pitted, and enveloped in an epidermis of brown, usually banded; mouth small, circular; lip continuous, simple, sometimes flaring. Tropical. The finest species are in the New World.

The Giant Cyclotus (C. giganteus, Gray) has a flattened spire of rounded whorls, the rich chestnut surface banded with a darker brown and stained with olive. The flaring lip and circular, spiral operculum are white, tinged with brown. This handsome snail frequents the woods of Panama. Diameter, 2 inches.

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