320 



BEPTILES. 



[Chap. IX. 



In undergoing this change, it is chiefly the organs 

 of respiration that manifest alteration. In its earliest 

 form the young batrachian, living in the water, breathes 

 as a fish does by gills, either free and projecting as in 

 the water-newt, or partially covered by integument as 

 in the tadpole. But the gills disappear as the lungs 

 gradually become developed : the duration of the pro- 

 cess being on an average one hundred days from the time 

 the eggs were first deposited. After this important 

 change, the true batrachian is incapable any longer of 

 living continuously in water, and either betakes itself 

 altogether to the land, or seeks the surface from time to 

 time to replenish its exhausted lungs. 1 



The change in the digestive functions during meta- 

 morphosis is scarcely less extraordinary ; frogs, for 

 example, which feed on animal substances at maturity, 

 subsist entirely upon vegetable when in the condition 

 of larvae, and the subsidiary organs undergo remarkable 

 development, the intestinal canal in the earlier stage 

 being five times its length in the later one. 



Of the family of tailed batrachians, Ceylon does not 

 furnish a single example ; but of those without this 

 appendage, the island, as above remarked, affords many 

 varieties; seven distinguishable species pertaining to 

 the genus rana, or true frogs with webs to the hind 

 feet ; two to the genus bufo, or true toads, and five to 

 the Polypedates, or East Indian " tree-frogs besides a 

 few others in allied genera. The €S tree-frog," whose 



1 A few Batrachians, such as the with lungs in mature age, they are 



Siren of Carolina, the Proteus of not capable of living out of the. 



Illyria, the Axolotl of Mexico, and water. Such batrachians form an 



the Menobranchus of the North intermediate link between reptiles 



American Lakes, retain their gills and fishes, 

 during life ; but although provided 



