434 Glossary. 



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 (pi. 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 collar-bones in many 

 birds, such as the common Fowl. 



Gallinaceous Birds. — 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. 

 Ganoid Fishes. — Fishes covered with peculiar enamelled bony scales. 



Most of them are extinct. 



Germinal Vesicle. — A minute vesicle in the eggs of animals, from which 



the development of the embyro proceeds. 

 Glacial Period. — 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 crystals of felspar and mica in 



a mass of quartz. 



Habitat. — The locality in which a plant or animal naturally lives. 



Hemiptera. — An order or sub-order of Insects, characterised by the posses- 

 sion 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 deve- 

 lopment from corresponding embryonic parts, either in different animals, 

 as in the case of the arm of man, the fore-leg 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 appen- 

 dages 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 



