320 
REPTILES. 
[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 " 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 forcnan 
the Menobranchus of the North intermediate link between reptiles 
American Lakes, retain their gills and fishes, 
during life ; but although provided 
