CHAPTER XXV 



BRANCH CHORDATA (Continued). CLASS BA- 

 TRACHIA: THE BATRACHIANS 



THE structure, life-history, and habits of the garden- 

 toad (Bnfo Icntiginosus} have already been studied (see 

 Chapter II and Chapter XII). 



OTHER BATRACHIANS. 



The class Batrachia includes the animals familiarly 

 known as coecilians, sirens, mud-puppies, salamanders, 

 toads, and frogs. Although differing plainly from fishes 

 in appearance and habits, the batrachians are really closely 

 related to them, resembling them in all but a few essential 

 characters. Among the distinctive characters of ba- 

 trachians may be noted the absence of fins supported 

 by fin-rays, the presence usually of well-developed legs 

 for walking or leaping, and the absence or reduction of 

 certain bones of the head connected with the gills and 

 lower jaw and which are well developed in the fishes. 

 The batrachians stand in somewhat intermediate position 

 between the fishes and the reptiles, showing some of the 

 characters of both. They are, like fishes and reptiles, 

 cold-blooded. In their adult condition some are terres- 

 trial and some aquatic as to habitat, but all have an aquatic 

 larval life. The water-inhabiting young breathe at first 

 by means of gills, later lungs begin to develop, and for a 

 time both gills and lungs are used in respiration. Finally 

 in the adult condition in almost all of the forms the gills 



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