FROG

the common English name of a number of animals belonging to the cla Amphibia, having four legs 590 - FROISSART with four toes on the fore feet and five on the hind, more or le webbed, a naked body, no ribs, and no tail. Owing to the last peculiarity frogs belong to the order of amphibians known as Anura or taille Amphibia. They constitute the family Ranide, which ranges over most of the world, except Australia (save the extreme north-east), New Zealand, and South America (south of the equator). Typical species are the common or gra frog (Rana temp oraria), edible frog (R. esculent a), and the bull frog (R. catesbiana) of North America. The tongue is fieshy, and is attached in front of the jaw, but is free behind, so that its hinder extremity can be shot out to catch insects. Frogs are remarkable for the transformations they undergo before arriving at maturity. In the spring the spawn is deposited in ponds and other stagnant waters in large ma es, each blackish egg being surrounded by a gelatinous sphere. The eggs hatch out into fishlike tadpoles, which at first breathe. by external and later on by internal gills. The adult form is reached by lo of gills and tail, and the development of lungs and limbs. Frog, in engineering, two short pieces of rail. They are joined together to form an angle between the railway lines at a railway cro ing or at a point where the rails lead to a siding, serving to guide the wheels of a train from one set of lines to another. When used at a cro ing the contrivance is termed a cro frog.