Rocks of this age contain a small proportion of shells identical with species now living. EPHEMEROUSINSECTS Insects allied to the May-fly. FAUNA The totality of the animals naturally inhabiting a certain country or region, or which have lived during a given geological period. FELIDÆ The Cat-family. FERAL Having become wild from a state of cultivation or domestication. FLORA The totality of the plants growing naturally in a country, or during a given geological period. FLORETS Flowers imperfectly developed in some respects, and collected into a dense spike or head, as in the Grasses, the Dandelion, &c. FOETAL Of or belonging to the foetus, or embryo in course of development. FORAMINIFERA A class of animals of very low organisation, and generally of small size, having a jelly-like body, from the Surface of which delicate filaments can be given off and retracted for the prehension of external objects, and having a calcareous or sandy shell, usually divided into chambers, and perforated with small apertures. FOSSILIFEROUS Containing fossils. FOSSORIAL Having a faculty of digging. The Fossorial Hymenoptera are a group of Wasp-like Insects, which burrow in sandy soil to make nests for their young. FRENUM(pl FRENA). A small band or fold of skin. FUNGI(Sing FUNGUS). A class of cellular plants, of which Mushrooms, Toadstools, and Moulds, are familiar examples. FURCULA The forked bone formed by the union of the collarbones in many birds, such as the common Fowl. GALLINACEOUSBIRDS An order of Birds of which the common Fowl, Turkey, and Pheasant, are well-known examples. GALLUS The genus of birds which includes the common Fowl. GANGLION A swelling or knot from which nerves are given off as from a centre. GANOIDFISHES Fishes covered with peculiar enamelled bony scales. Most of them are extinct. GERMINALVESICLE A minute vesicle in the eggs of animals, from which development of the embryo proceeds. GLACIALPERIOD A period of great cold and of enormous extension of ice upon the surface of the earth. It is believed that glacial periods have occurred repeatedly during the geological history of the earth, but the term is generally applied to the close of the Tertiary epoch, when nearly the whole of Europe was subjected to an arctic climate. GLAND An organ which secretes or separates some peculiar product from the blood or sap of animals or plants. GLOTTIS The opening of the windpipe into the oesophagus or gullet. GNEISS A rock approaching granite in composition, but more or less laminated, and really produced by the alteration of a sedimentary deposit after its consolidation. GRALLATORES The so-called Wading-birds (Storks, Cranes, Snipes, &c.), which are generally furnished with long legs, bare of feathers above the heel, and have no membranes between the toes. GRANITE A rock consisting essentially of crystal of felspar and mica in a mass of quarts. HABITAT The locality in which a plant or animal naturally lives. HEMIPTERA An order or sub-order of Insects, characterised by the possession of a jointed beak or rostrum, and by having the fore-wings horny in the basal portion and membranous at the extremity, where they cross each other. This group includes the various species of Bugs. HERMAPHRODITE Possessing the organs of both sexes. HOMOLOGY That relation between parts which results from their development from corresponding embryonic parts, either in different animals, as in the case of the arm of man, the foreleg of a quadruped, and the wing of a bird; or in the same individual, as in the case of the fore and hind legs in quadrupeds, and the segments or rings and their appendages of which the body of a worm, a centipede, &c., is composed. The latter is called serial homology .
The parts which stand in such a relation to each other are said to be homologous , and one such part or organ is called the homologue of the other.
