VERTEBRATA. 



251 



legs. The aquatic Newts and land Salamanders drop 

 their gills, and always have four limbs. 



Order 2. Labyrinthodontia (labyrintkos, a labyrinth, 

 odous, a tooth) are now all extinct. They resembled gi- 

 gantic Salamanders, except in their complex teeth and 

 exoskeleton of bony plates. 



Order 3. GymnopJiiona, (gymnos, naked ; ophis, a snake,) 

 also called Cecilia. They have neither tail nor limbs, a 

 snake-like form, minute scales in the skin, and numerous 

 ribs. 



Order 4. Batrachia, or Anoura. (Fig. 149.) (Batrachos, 

 frog ; ana, without ; oura, a tail.) These are tailless 



FIG. 149. i. Frog, (Rana temporaria.) 2. Toad, (Bufo vulgaris?) 3. Tadpoles. 



Amphibia, and comprise Frogs and Toads. They have 

 a naked, moist skin, ten vertebrae, and no ribs. They 

 have four limbs, the hinder longer than the fore-legs. 

 They have four ringers and five toes. The tongue is 

 long, fixed at the anterior, and doubled up. It can be 

 thrown out rapidly as an organ of prehension. The eggs 

 are laid in the water, enveloped in a glairy mass, and the 



