FROG. 157 



others, but there does not appear to be any good grounds for 

 this differentiation. 



The Viper is found in all parts of Britain, but is not known 

 in Ireland. 



Frog (Ra?ia temporaria, Linn.). 



With the Common Frog, popularly classed as a Reptile, we 

 commence acquaintance with the zoological class Batrachia, 

 creatures that begin life at a much lower stage of development 

 and have to pass through a fish-like larval form before attaining 

 to any likeness to their parents. The Reptiles get through 

 these developmental stages whilst they are still in the egg ; 

 they never have water-breathing organs. The Batrachians or 

 Amphibians are clothed with soft skin which is not protected 

 by armour plates or scales as seen in the Lizards and Snakes, 

 but through which they are able to oxygenate the blood. The 

 Frogs, Toads, and Newts constitute a class intermediate in 

 structure and development between the Fishes and the Reptiles. 

 Our native species represent the two orders Ecaudata (tail- 

 less), including the Frogs and Toads ; and Caudata (tailed) 

 comprising the Newts. 



Everybody knows the Frog as well as they know any of the 

 backboned animals, and every youngster even is familiar with 

 the main facts of its development, from the jelly masses of eggs 

 in the pond early in spring, through the tadpole stage to the 

 attainment of four legs and wonderful leaping powers. It is 

 common knowledge that he has a moist, smooth skin (the 

 supersensitive erroneously say u slimy") of yellowish ground 

 colour overlaid with streaks and spots of brown. There is a 

 big patch of brown behind each eye, and the long hind legs 

 have cross-bars of the same colour. The ground tint of the 

 Frog varies in different individuals according to the situation 

 in which we may find them ; for the pigment cells of the skin 

 expand and contract under the influence of varying intensities 



