Distinguished from the Natica by the great width of the aperture, and its short spiral columella. Shell oval, more or less thick, very depressed, spiral short, little elevated, lateral; aperture very extended, entire, the left edge reflected and sharp; two lateral muscular impressions very disunited. Sigaretus Haliotoideus. S. convexus. S. lævigatus. S. cancellatus. _S. convexus._ The convex Sigaretus. Pl. 22, fig. 2. Very thin, smooth, back convex, spire white, rather prominent; aperture very expanded; umbilicus rather deep; yellow, with a reddish tinge, transversely striated. _S. Haliotoideus._ The Haliotis-shaped Sigaretus. Species thick, solid, depressed; spire flattish, aperture exposing the whole of the interior. 2. Stomatella. Five species. To be easily distinguished from the Stomatia by not having a transversal rib. Shell very depressed, orbicular or oblong; imperforate; interior pearly; aperture very large, oval, longer than wide; the right edge effuse, dilated, and open; summit pointed and incurved. Stomatella imbricata. S. rubra. S. sulcifera. S. auricula. S. planulata. _S. imbricata._ The imbricated Stomatella. Pl. 22, fig. 1. Sub-orbicular, convex, sub-depressed, rough, covered with imbricated scales; colour grayish brown. _S. auricula._ The ear-shaped Stomatella. Species oval, elongated. 3. Stomatia. Two species. Bearing a very great resemblance to the Haliotis, but is never perforated. Shell ear-shaped, imperforate; oblong, spire elevated and recurved to one side; aperture entire, oblong; interior pearly; tuberculated, and with a transverse sub-carinated rib. _S. phymotis._ The tumoured Stomatia. Pl. 22, fig. 6. Elongated oval, striated, tuberculated; spire small, contorted; lip thin and sharp, colour white, interior pearly. 4. Haliotis. The Ear Shell. Fifteen species. This genus is very beautiful, and derived its common name from its resemblance to the human ear. The exterior is generally tuberculated and loaded with marine substances, which gives it a rough and uncouth appearance, but the interior forms a splendid contrast by its natural iridescence. Each shell is furnished with a row of orifices near the margin, varying in number from eight upward; of these from three to seven are generally open, and the others close. These holes are made by the animal as it increases the size of the shell, to admit the passage of a short syphon. They are found adhering to rocks like the Patella, and are detached with great difficulty.