284 REPTILES. 



observer would scarcely detect any difference between a frog and 

 a newt. 



The Frogs (Rand) are too well known to need description. The energetic 

 movements of the Common Frog (Rana temporaria) command general admi- 

 ration. The length of its leaps and its vigorous action in swimming depend 

 on the great development of the hinder limbs. These animals feed on slugs 

 and insects, which they seize by means of their tongue, the arrangement of 

 which is very curious. When at rest the tongue is doubled back upon itself, 



FIG. 306. SKELETON OF FROG. 



so that the tip is directed towards the throat : in seizing a fly or beetle it is 

 launched forth like lightning, and as quickly retracted, with the captive prey 

 adhering to its extremity. The accompanying figure of the skeleton of the 

 frog may be compared with that of the salamander on a previous page. It 

 will be seen, with many points in common, to present important differences, 

 particularly the small number of joints in the spine, the great size of the 

 pelvis, or bony framework at the hinder part, and the enormous develop- 

 ment of the hinder limbs. The frog has no trace of ribs, which in the newts 

 do exist, though very small. 



Frogs are distinguishable from toads by a row of teeth all round the upper 

 jaw. They feed only on living prey. In winter they bury themselves in the 

 mud or in holes, and do not eat. 



The Tree-Frogs (Hyla) do not differ much from ordinary frogs, except 

 that the extremity of each of their toes is enlarged and rounded into a sort of 

 viscid pellet or ball, that enables them to adhere to objects upon which they 

 climb, and to ascend trees. Endowed with great suppleness and agility, 

 tree-frogs travel very lightly over the most flexible branches. During the 

 whole summer they live in this manner on trees, pursuing insects, but in 

 winter they retire to the bottom of the water, like ordinary frogs, and do not 

 return again to the humid foliage where they reside until after they have de- 

 posited their eggs. The Common Tree-Frog (Rana arboria) is of an apple- 

 green colour above, and pale beneath, with a black and yellow line along each 

 side. 



