"Look carefully at those three shells: do you perceive much resemblance between them? 'Not much, if any,' you reply, yet they are all of the genus _Bulla_. Here is _B. lignaria_, _B. terebellum_, (see Frontispiece,) and _B. naucum_. (Plate 6.) There are other forms, as the _B. ovum_, _B. volva_, the first somewhat like a cowry; but it is toothed only on one side of the aperture; the second has two long beaks. "This genus is confessedly ill-determined. _B. naucum_ and _B. ampulla_ are examples of the common characters of the genus. The species are sixty-one. [Sidenote: VOLUTA. BUCCINUM.] "_Voluta_ is also a large genus, containing one hundred and eighty-six species. Shell univalve, aperture without a beak, and somewhat effuse; columella _plaited_. This latter character we meet with for the first time. Here is the common _Voluta_. (Plate 6.) The genus has been much diminished by forming other very striking genera out of it, as I shall soon show you, under the names of _Mitres_, _Olives_, _Gondolas_, &c. _Voluta musica_, the music-shell, is remarkable, and not at all rare. "_Buccinum_ is another large genus. The shell univalve, spiral, gibbous; aperture ovate, ending in a canal turning to the _right_, with a short beak; pillar-lip expanded. Species, one hundred and seventy-two. "You must recollect that when the apex of the shell is turned _downwards_ the canal turns to the right, when it is turned _upwards_ the canal will be to the left hand. My example is _Buccinum reticulatum_, a very common species upon our own shores." (Plate 7.) "Is not this genus reduced by other authors?' asked Charles. "Greatly," replied Mr. Elliot: "you will meet with tuns, helmets, harps, and needles. Species of the _Buccinum_ genus are found in the African, American, Indian, European, and Southern oceans. Eighteen occur upon our coasts. [Sidenote: STROMBUS. MUREX.] "_Strombus_ contains forty-four species. Shell univalve, spiral, aperture much dilated, the lip expanding, ending in a canal inclining towards the left. "You must notice the sinus in the outer lip, near the base of the shell. _Strombus gigas_, the West Indian conch, is very large. Some species have the lip ending in claws. _Strombus pes-pelicani_, the pelican's-foot, has four palmated claws: (Plate 7.) it is a British shell. The city of Santa Cruz, in America, is paved with the shells of _Strombus gigas_. "The genus _Murex_ is both large and beautiful. Shell univalve, spiral; aperture oval, ending in a straight canal. "These shells are of very unequal form; their surfaces frequently covered with spines, knobs, or foliations. Some are remarkable for the great length of the beak, (Frontispiece,) such as the woodcock, the snipe's-head, and Venus's-comb. The _Murex_ before you is foliated. (Plate 7.) The species are one hundred and seventy-one. Several are found on British coasts, but they are not remarkable for beauty.