98 



METAMORPHOSIS OF BATRACHIA. 



loosely in the water on either side of the head. At a later 

 period, however, these gills, which are merely temporary, 

 disappear ; and the breathing is carried on by another set, 

 which are situated behind the head, and are covered in by a 

 fold of skin; the water gains access to these by passing 

 through the mouth, exactly as in Fishes. The form is then 

 that which is represented in fig. 36. In a short time after- 

 wards, the animal still breathing by its gills, the hind-legs 

 begin to sprout forth, as it were, at the base of the tail ; this 



Fig. 36. 



Fig. 37. 



Fig. 35. 



Fig. 39. 



stage is shown in fig. 37. At a still later period, the fore- 

 legs begin to be developed, as seen in fig. 38 ; and from that 

 time they are nourished at the expense of the tail, which 

 gradually disappears, as seen in fig. 39, a, b. During ^this 

 period, other important changes are taking place in the inte- 

 rior of the body ; the chief of which are the development of 

 the lungs and the gradual disuse of the gills, so that the 

 animal becomes fitted to live on land and breathe air, and is 

 no longer capable of remaining long under water without 

 coming to the surface to respire. 



87. The metamorphosis in other members of the group is 



