INTRODUCTION TO THE CLASS OF AMPHIBIANS 127 



to formulate a general statement regarding amphibians which 

 will not be open to exceptions. If the reader will bear this 

 in mind, we may venture to state the leading characters of 

 the members of this Class. 



General Characteks.^AU save a very few amphibians 

 are hatched from soft, translucent, jelly-like eggs that are 

 laid in shallow water, usually in stringy masses. Sometimes 

 the larval stage of a species is passed in the egg, but usually 

 this period forms an important part of the active life of the 

 animal, and may be observed at length before the change to 

 the adult stage takes place. Amphibians are (usually) cov- 

 ered with smooth skins, quite destitute of scales, and have 

 minute teeth, or none at all. During the larval stage they 

 feed chiefly upon vegetable food, but when adult the ma- 

 jority require animal food. Their skeletons are much more 

 simple in structure than those of reptiles. The majority are 

 aquatic. Some species permanently retain their gills, and 

 live wholly in water; others, like the frogs and toads, lose 

 their gills, acquire practical lungs and legs, and live upon 

 land at will. Of the 1,040 species of amphibians, only forty 

 are without legs. 



An amphibious animal is not necessarily an amphibian. 

 The hippopotamus, the seal, sea-lion, otter and crocodile 

 are indeed very much at home in water, but they are far 

 above the Class Amphibia. They are by no means creatures 

 of two lives, and they do not pass through a larval stage 

 before attaining perfect form. 



Like the reptiles, the amphibians are confined to the tor- 

 rid and temperate zones, but a surprising number of species 



