These shells have received their name from their resemblance in form
to a boy’s top. They are all marine shells, and the apex of their
spire is always very sharp-pointed. In some places they are called
_flat-mouthed snails_. The greater number of these shells, (and the
species are very numerous,) are of a beautiful pearly substance, and
many of them are also elegantly marked with longitudinal ribs; there
are as many as seventy species,—the larger and more elegant are only
found in the seas of hot climates.
[Illustration: _Haliotis iris. Scalaria pretiosa. Neritina pulligera._]