Shell solid, adhering, sub-regular, more or less spined, sub-auriculated, inequivalve; the right or inferior valve fixed, much more excavated than the other, and having behind, at the summit, a triangular face, which enlarges and elongates with age; hinge longitudinal, provided in each valve with two strong teeth entering into corresponding cavities; ligament short, almost medial, partly exterior; one sub-dorsal, muscular impression.
Spondylus gædaropus.
S. Americanus.
S. arachnoides.
S. candidus.
S. multilamellatus.
S. coccineus.
S. crassisquama.
S. spathuliferus.
S. ducalis.