REPTILES 



221 



being the only one which extends into the New World as well 

 as the Old. Typical species are the Gangetic Soft Tortoise 

 (Trionyx Gangeticus), the Nilotic Soft Tortoise (T. triunguis] 

 (fig. 137), which feeds largely on the eggs and young of the 

 crocodile, and the common 

 American Soft Tortoise (T. 

 ferox), a native of the North 

 American streams which flow 

 into the Gulf of Mexico, and 

 noted as a destroyer of the 

 alligator's eggs and young. 



Order 3. LIZARDS 

 (Lacertilia) 



The large Lizard order, of 

 which a fair average sample 

 has already been described 

 at some length, embraces re- 

 presentatives in all parts of 

 the globe except the polar 

 regions, and includes no less 

 than twenty families, contain- 

 ing about 1700 species. It 

 will only be possible here to 

 mention a few of the more 

 interesting forms, included 

 in the families of i. Geckos; 

 2. Scale-footed Lizards; 3. 

 Agamoids; 4. Iguanas; 5. 

 Snake- Lizards; 6. Venomous 

 Lizards ; 7. Monitors ; 8. 

 Common Lizards; 9. Skinks; 

 and 10. Chameleons. 



i. Geckos are small noc- 



* I 



Fig. 138 Wall Gecko (Tarentola Mauritanica} 



turnal lizards, with large eyes, and lobed feet adapted for climbing. 

 They are found in all the warmer parts of the earth, and the Wall 

 Gecko (Tarentola Maiiritanica) (fig. 138) of the Mediterranean 

 shores is the most familiar example. One structural feature of 

 the family deserves notice here, i.e. the shape of the centra of the 

 vertebrae. These are biconcave, a very primitive feature specially 



