BULLFROG AS TYPICAL VERTEBRATE ANIMAL 103 



In the southern states, bullfrog legs have been a favorite food for 

 years. Within recent years businesses have developed which are de- 

 voted to supplying bullfrog legs, and the demands for these from 

 all parts of the country have been so great that it may become 

 necessary to afford some protection to prevent the rapid depletion 

 of these animals. Attempts have been made to operate frog farms 

 and raise a supply. Most of these attempts have been failures be 

 cause of the high overhead cost. The axolotl is used in Mexico as 

 food ; and water dogs, such as our Necturus, are reputed to have a 

 good flavor. 



Dried frogs and toads have been used in China both as a source 

 of food and for medicinal purposes. It is reported that toad skins 

 have been used in Japan and elsewhere for making a fine type of 

 leather. Dried salamanders have been used as a vermifuge. Adult 

 frogs and salamanders, as well as larval stages, are widely used as 

 laboratory animals. 



Classificatioii of Amphibia 



There are estimated to be about 1,900 known species of living 

 frogs, toads, and salamanders in the world, and about 60 species 

 of caecilians. None of the caecilians have been reported from the 

 United States. In the United States there occur about 70 species 



Fig. 36. — Amhystotna texanum, a very common salamander in Texas. (Photograph 



by Ottys Sanders.) 



of salamanders and about 67 species of frogs and toads. Many of 

 these species are subdivided into several subspecies. The Southwest 

 contains a large proportion of all of these, and Texas has within 

 its boundaries more species of toads than does any other state in 

 the Union. 



Some characters used in classifying salamanders are : the presence 

 or absence of gills, either external or internal ; color markings ; 

 shape and appearance of body; length; number of costal grooves; 



