CLASS AMPHIBIA 



59 



ectoderm represents the beginning of the eye, and just above the 

 gills (E, br.i, br.2) appear the invaginations which form the 

 vesicles of the inner ears. The markings of the muscle segments 

 show through the skin along the sides of the body and tail. 



FIG. 426. Tadpoles in different stages of development, from those just 

 hatched (i) till the adult form is attained (8). (From Mivart.) 



The embryo moves about within the egg by means of cilia, 

 but these soon disappear after hatching. The tadpole, after 

 breaking out of the egg membranes, lives for a few days on the 

 yolk in tHfe alimentary canal, and then feeds on algae and other 

 vegetable matter. The external gills grow out into long, branch- 

 ing tufts (Fig. 426, 2, 2 a). Four pairs of internal gills are formed 



