GRYPHÆA. Lam. (From Gryps, a griffin.) _Fam._ Ostracea, Lam.--_Descr._ Inequivalve, free; lower valve large, concave; with the umbo prominent, incurved; upper valve small, flat, opercular; hinge toothless, with a curved, depressed area; one muscular impression.--_Obs_. These shells, which approach the Oysters, are of a more regular form, and are remarkable for the curved, produced beak of the lower valve. They are only known in a fossil state, belonging to the more ancient strata. Fig. 182, G. incurva. The recent species mentioned by Lamarck is not a true Gryphæa. GYMNOLEPAS. A generic name used by De Blainville to include OTION and CINERAS, Leach. GYMNOSOMATA. Bl. The second family of the order Aporobranchiata, in the system of De Blainville. The animals belonging to this family are destitute of shells. GYPIDEA. Dalman. A genus of Brachiopoda, thus described, "Larger valve with the umbo rostrated, remote from the hinge; with the canal large, deltoid; bilocular within." PENTAMERUS, Sow. Fig. 210. 211, G. Conchidium, copied from Dalman. GYROGONA. Lam. A genus of microscopic Foraminifera. GYROIDINA. D'Orb. A genus of microscopic Foraminifera. HALIOTIDÆ. Sw. A sub-genus of Calyptræa. CALYPTRÆA dilatata. Sowerby's Genera of Shells, fig. 9. HALIOTIS. Auct. ([Greek: als], _als_, sea; [Greek: ous], [Greek: ôtos], _otos_, ear.) _Fam._ Macrostomata, Lam. Otides, Bl.--_Descr._ Auriform, broad, depressed, pearly within, rough, costated, tuberculated without; spire short, flat, consisting of one or two whorls; aperture wide; ovate; columella laminar, flat, oblique; a spiral series of perforations running along the dorsal margin.--_Obs._ The splendid shells belonging to this genus are remarkable for the pearly iridescence of the inner surface, and the row of holes following the course of the spire. The soft parts are eaten in Guernsey and Jersey, and reckoned delicious. They belong to temperate and tropical climates. Fig. 338, H. rubra. 339, Padollus, Montf. HALIOTOID. (_Haliotis_ and [Greek: eidos], _eidos_, form.) Ear-shaped. HAMIFORM. (_Hamus_, a hook.) Curved at the extremity. HAMITES. Parkinson. (_Hamus_, a hook.) _Fam._ Ammonacea, Lam.--_Descr._ Elongated, cylindrical, chambered, recurved at the smaller extremity, annulated; septa lobed and sinuated.--_Obs_. This remarkable fossil from the Baculite limestone in Normandy, differs from Baculites in being curved at one extremity, a circumstance from which its name is derived. Some small species are found in Chalk-Marle, Folkstone. Fig. 484*. H. cylindricus.