426 APPLIED BIOLOGY 



nearly $50,000 worth of wild frogs will soon exterminate them 

 unless " frog-farms " are more extensively developed in the 

 near future. But the chief value of our common amphibians 

 is in that they destroy thousands of insects. The common 

 toad is a valuable inhabitant of gardens. See the bulletin 

 on the American toad which is published (free) by the 

 United States Department of Agriculture, and also see a 

 chapter in Hodge's " Nature Study and Life." We ought to 

 have laws protecting toads as well as birds, but until we get 

 such laws we must depend upon the good sense and fair play 

 of intelligent people who are informed concerning the value 

 of toads. Frogs are likewise useful as destroyers of insects, 

 but have not attracted so much attention as the toad, which 

 is able to go far from bodies of water. They could be kept 

 in gardens without small ponds. 



The species of tailed amphibia which spend much time on 

 land are probably useful destroyers of insects. 



Important Orders of Amphibia 



Urodela with tail, usually two pairs of limbs, and may have gills 



in adult. Examples : newt, salamander. 

 Anura, or Batrachia no tail and no gills in adults. Two pairs of 



limbs. Frogs and toads. 

 For interesting reading and reference : Diekerson's " Frog Book." 



REPTILES 



352. The class Reptilia contains four types represented 

 by the existing lizards, snakes, turtles, and crocodiles, of 

 which there are about 3500 living species. All these types 

 of reptiles have scales on the skin. In turtles the scales are 

 large plates (e.g., the valuable tortoise shells), which form 

 the outer surface of a box-like shell. Typically the reptiles 

 have four legs with five toes each. The legs have degenerated 

 in snakes, but certain pythons and boas possess rudiments of 

 the hind pair of legs. Colors are well developed in the skin 



