REPTILES 1381 



become obliterated. The true gills, or branchia, 

 are contained within the body, and are four in num- 

 ber on each side, constructed on a plan very similar 

 to those of fishes. Retaining this aquatic constitution, 

 the tadpole rapidly increases in size and in activity 

 for several weeks. In the meantime the legs, of 

 which no trace was at first apparent, have com- 

 menced their growth. The hindlegs are the first to 

 make their appearance, showing their embryo forms 

 within the transparent coverings of the hinder part 

 of the trunk, just at the origin of the tail. These are 

 soon succeeded by the forelegs, which exactly follow 

 the hindlegs in all the stages of their development, 

 until they have acquired their due proportion to the 

 size of the trunk. The animal at this period wears a 

 very ambiguous appearance, partaking of the forms 

 both of the frog and of the lizard, and swimming 

 both by the inflexions of the tail and the irregular 

 impulses given by the feet. This interval is also em- 

 ployed by this amphibious being in acquiring the 

 faculty of respiring atmospheric air. We observe it 

 rising every now and then to the surface, and cul- 

 tivating its acquaintance with that element, into 

 which it is soon to be raised; occasionally taking in 

 a mouthful of air, which is received into its newly 

 developed lungs, and afterward discharging it in 

 the form of a small bubble. When the necessary in- 

 ternal changes are at length completed, preparations 

 are made for getting rid of the tail, which is now a 

 useless member, and which, ceasing to be nourished, 

 diminishes by degrees, leaving only a short stump, 

 which is soon removed. The gills are by this time 



