The _Haliotides_, or sea-ears, are very splendid shells; the species
are numerous, and some of them are extremely common. The place in the
system which this shell ought to occupy, appears to have caused many
doubts in the minds of modern naturalists, and consequently, we find it
continually shifted from one part to another in the different works of
Lamarck and Cuvier. When moving from place to place in search of food,
the animal and its shell present a very pleasing sight, the slender
tentacula which appear through the different holes which ornament
the margin of the shell, gracefully waving in all directions; these
tentacula are supposed to be breathing-tubes. In the young shell, the
number of perforations is not so great as in an adult, one being formed
at each progressive stage of the creature’s growth. Sometimes the holes
which were first formed become, by age, filled up. The proportions of
the shell, also, vary materially, so as to render the separation of
species very difficult and uncertain.