HO* THE ANIMAL KINGDOM. 



like those of a fish, but hang outside, like a fringe, and, 

 strangely enough, they may be removed and yet the animal 

 remain alive, as it is provided with lungs as well. It has 

 four short limbs, which are very feeble, the front pair 

 having three fingers each, whilst the hinder ones have 

 but two. 



A whole family of these amphibious reptiles which 

 lose their gills at a certain period of their lives, is sepa- 

 rated from the others, and classed under the name of 

 Batrachia, and these comprehend the groups of Newt, 

 Frog, and Toad-like animals. 



When the young of the frog issues from the egg, the 

 gills are only little lumps on each side of the head. These 

 soon branch out, as shown in Fig. 71 ; it then has a long 

 tail, and its gills hang loosely in the water. This figure is 

 drawn larger than it should be in proportion to the 

 others, in ordef- to show the gills plainly. These gills 

 after a while die off, and breathing is performed by another 

 set at the back of the head, the water passing over them 

 through the mouth, as in fishes ; the animal then appears 

 as shown in Fig. 72. 



Up to this stage they are called Tadpoles, but soon after 

 the hind legs begin to show themselves (Fig. 73), and the 

 lips are covered with a sort of horny beak, which enables 

 it to fix itself on vegetable matter, on which it feeds ; at a 

 later period, the front legs make their appearance (Fig. 

 74). During the time these changes take place externally, 

 the true lungs are being formed internally, and the gills 

 are no longer used, and disappear ; the horny beak falls 

 off, the animal changes its food, and becomes carnivorous. 

 The little frog cannot now remain long under water, but 

 has to come to the surface to breathe. Gradually the 

 tail becomes shorter, as shown in Fig. 75 ; eventually it 

 disappears altogether, and the animal has reached its 

 perfect form (Fig. 76). The complete skeleton of a 



