Flora, the complete system of vegetable species native in a given locality, or period. Fluor-spar, a mineral of beautiful colors, composed by fluorine and calcium. Fluvio-marine, the deposits formed by the joint action of a river and the sea. Foramen, a little opening. Fossa, a depression in a bone. Fossil, the form of a plant or animal in the strata composing the surface of the earth. Genus (pl. genera), an assemblage of species possessing certain characters in common, by which they are distinguished from all others. Geode, an irregular shaped stone, containing a small cavity. Geognostic, pertaining to a knowledge of the structure of the earth. Glabella, the middle or frontal protuberance of the superciliary arch. Glaciation, the process of becoming covered with glaciers. Glacier, an immense mass of ice, or snow and ice, formed in the region of perpetual snow, and moving slowly down mountain slopes or valleys. Gneiss, a crystalline rock, consisting of quartz, feldspar, and mica. Herbivora, that order of animals which subsists upon herbs or vegetables. Homologous, having the same typical structure. Humerus, the bone of the arm nearest the shoulder. Hybrid, that which is produced from the mixture of two species. Ilium, the upper part of the hip bone. Jade, a hard and compact stone, of a dark green color, and capable of a fine polish. Lambdoidal, the suture which connects the occipital with the parietal bones. Leptinite, a fine-grained granitic rock. Loam, a soil composed of siliceous sand, clay, carbonate of lime, oxide of iron, magnesia, and various salts, and also decayed vegetable and animal matter. Loess, a term usually applied to a tertiary deposit on the banks of the Rhine. Lumbar, the vertebræ near the loins. Mammalia, that class of animals characterized by the female suckling its young. Marl, a mixed earthy substance, consisting of carbonate of lime, clay, and siliceous sand. Mastoid, a process situated at the posterior part of the temporal bone. Matrix, a mould; the cavity in which a thing is held. Maxillary, the upper jaw bone. Metacarpal, the part of the hand between the wrist and the fingers. Metallurgy, the art of working metals. Metatarsal, the middle part of the foot. Miocene, the middle or second epoch of the Tertiary. Molar, a grinding tooth. Mold, or mould, a prepared cavity used in casting; to form or shape; fine soft earth. Mollusca, an order of invertebrate animals having a soft, fleshy body, which is inarticulate, and not radiate internally. Moraine, a line of blocks and gravel extending along the sides of separate glaciers, and along the middle part of glaciers formed by the union of one or more separate ones. Nebulous, having a faint, misty appearance; applied to uncondensed gaseous matter.