THE HORSE-HOOF SHELLS Genus AMALTHEA, Schum. (HIPPONYX, Defr.) Shell thick, obliquely conical; apex hooked backward, not spiral; surface roughened; muscle scar horseshoe shaped; body oval; foot thin; head round, on slender neck; tentacles bearing eyes. Instead of an operculum, a shelly base is formed.
The Shell (A. antiquata, Linn.) is found in Florida and California and in many other sub-tropical regions.
It is a concave, hoof-shaped white shell with a hairy epidermis covering the scaly growth lines. The shape is variable, for the animal lives attached to rocks. It secretes a calcareous plate between the body and the object to which it adheres. Sowerby thought this was a second valve of the shell, and so described five species as a genus of bivalve mollusks.
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