Survey of the Animal Kingdom 333 



scaleless. The paired legs usually have five digits. They are cold blooded. The 

 heart is three chambered (2 auricles and 1 ventricle). There are about 2,000 

 species of Amphibia. 



Examples: Frog (Figs. 208 to 219), toads, salamanders, and newts (Figs. 148- 

 150). 



B. 



Fig. 148. — Representatives of the class Amphibia (not to scale). A, bullfrog 

 (Rana catesbiana) ; B, common toad {Bufo sp.). (Copyright by General Biological 

 Supply House, Inc., Chicago.) 



Class 5 — Reptilia (rep -til' i a) (L. reptilus, reptile, from repere, to crawl). 

 — These animals have horny plates (scales) covering their body. They have paired 

 lungs in the adult with no gills. They are cold blooded. Their heart is three 

 chambered (2 auricles and 1 ventricle, the latter being partially divided). The 

 cranium (brain case) articulates with the vertebral column by a single occipital 

 condyle. Reptiles possess both amnion and allantois. There are 4,000 species 

 of reptiles. 



