THE CARRIER SHELLS - FAMILY XENOPHORIDAE. Shell top-shaped, flattened, with stones or shell fragments attached as it grows; foot small, divided unequally by a groove, anterior part the larger; operculum horny.
A single genus with few species, widely distributed in tropical seas.
Genus XENOPHORA, Fisch.
These remarkable mollusks, whose family name means "carriers of strangers," deceive and thus circumvent their enemies by glueing to the growing shells pebbles, fragments of rock or dead shells, or whole ones,if small enough to be carried. So an adult shell may bristle with "lady fingers "(Turritella) or ladder shells (Scalaria), making it look at first glance like a sea urchin, or one of the spiny-toothed shells of the Murex group. If instead of the spiral shells, saucer-shaped ones are used, bivalves, like heart shells and scallops, for instance, the mollusk is careful to set them with their convex sides downward so as not to catch and impede travel which, at best, is laborious business.
A decided taste is exhibited by individuals, possibly modified by the supply of building materials. Some shells bear only rock fragments. Others are adorned with shells. Scientists have named the first group "mineralogists," the second, " concholo gists." The mollusk carefully keeps the flat base of his shell free from these impedimenta, so that he may have free use of his faculties, and get a good living. From above he looks like a piece of conglomerate, a part of the sea bottom debris. Below, a mollusk, with molluscan appetite, looks out of the ample door way of his shell. We may almost credit him with shrewdness
and a sense of humour.
The foot is small and cleft. The larger half extends forward and fastens its hold upon some stable object. A mighty contrac tion of the foot muscle causes the clumsy creature to jump forward 154 The Carrier Shells dragging the trifling hind foot after. Thus the gait is anything but a smooth glide. It is a series of jumps, and a most laughable performance to behold.
The Shell Carrier (X. conehylisophora, Born.) is a top shaped, pale brown shell marked by fine striae overlying irregular wrinkles on the whorls. In the shell surface are inserted various dead shells, for the evident purpose of deceiving the mollusk's enemies. The shell is normally about two inches across. With its trimmings of heart shells and the like it often doubles this measure.
Habitat.— West Indies.
The Pebble Carrier (X. calculifera, Rowe) adorns the shell with bits of stone. This is a typical "mineralogist." Gracefully curved striations are concealed by the irregular decorations the mollusk superadds to Nature's efforts., Sometimes there is but a small circle of pebbles and shells of dainty and uniform size set around the shell more than half way to the peak. This exposes the main part of the shell, and seems to indicate that the mollusk chooses to make his roof beautiful at the risk of exposure. Diameter, 2 to 3 inches.
Habitat.— China.
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