The Agate Shells Family Achatinidae

THE AGATE SHELLS FAMILY ACHATINIDAE. Shell thick, ovate, with elongated spire, and ventricose body whorl; aperture oval, large, sometimes on the left side; columella twisted, arched; lips united by a shiny callus.

Some agate shells are larger even than the great Brazilian snails, Bulimus. They, too, lay white eggs, over an inch long. In truth the Achatinx in Africa are parallel in characters, as in latitude, with the Bulimi in South America. But the agates are tree snails, and so dare to be gaily marked, while Bulimus, the ground snail, must be dull.

Genus ACHATINA, Lam.

Shell oblong-oval; spire conical; aperture oval; whorls rounded, six to nine, sometimes sinistral; lips united by a shiny callus. About seventy-five species, living in trees. Tropical Africa.

A. variegata,

Lam., dull tan-coloured with broad streaks of dark brown running full length of the shell, is one of the largest species. Length, 6 to 8 inches. West Africa.

The Zebra Agate Shell (A. zebra, Lam.) is streaked with zigzag longitudinal lines of chestnut on a white ground. The shell is ovate. Length, 4 to 5 inches. Madagascar.

A. sinistrorsa,

Chemn., one of the largest agates, coils to the left. It has a lurid brownish body whorl, with bright, chesnut streaked spire. Length, 4 to 5 inches. Isle Principe, Africa.

A. reticulata,

Pfr., has a slender, creamy white spire of gracefully rounded coils, finely streaked and dotted with chestnut. The shiny surface is raised in fine rounded ridges crossed by close spiral grooves. Length, 6 to 8 inches. Africa.

A. purpura,

Chemn., horny outside, has a rosy lining. Length, 3 to 5 inches. West Africa.

The Panther Agate Shell (A. panthera, Pfr.), striped and tawny like its namesake, lives in hollows in the rocks and in trees, 275 The Agate Shells where it is protected from the sun. On the mainland it grows

larger than on the islands and the shell is thicker. The mollusk is omnivorous, eating when kept in captivity, meat, vegetables, dead snails — even pieces of old newspaper. One laid, in a snailery, two hundred small eggs.

The dry season drives them all into holes in rocks and trees. They often congregate, a dozen or more in one pocket. The shell is sealed with an opaque, papery epiphragm. Length, 2 to 4 inches. Mozambique and African coast.

Genus STENOGYRA, Shuttl.

Shell long, turreted, white or transparent; whorls many, delicate; aperture oval; lip simple, sharp. Two hundred and fifty species in tropical and temperate countries.

The Obelisk Stenogyra (S. obeliscus, Moric.), is a handsome, yellowish, auger-shaped shell, the last whorl about one-quarter the total length. Length, 3 to 4 inches. Width, 4 inch.

Habitat.— Tropical America, Natal, Philippines.

The Limy Stenogyra (S. calcarea, Born.) shows its calcareous substance by the scaling off of the chestnut brown epidermis. But little longer than S. obeliscus, it is much larger, its basal diameter is sometimes 1 inches. Brazil.

S. decollatus,

Linn., smooth, delicate, of pale livid hue, well illustrates the peculiar habit of building partition walls, and then dropping off the shell apex, by degrees. Moquin-Tandon reports that the mollusk jerks the shell against some hard object to break it off. The average specimen has four or five whorls remaining. This European species is established at Charleston, S. C. Length, to I inches.