CLASS REPTILIA 



413 



Figure 281. The western box turtle Terrapene. The under part of the shell is hinged and 

 encloses the animal as though it were in a box. This is a protective mechanism. The turtle is 

 known to live to the ripe old age of 123 years. (Courtesy of American Museum of Natural 

 History.) 



on other live animals. One of its most strik- 

 ing peculiarities, shared with many lizards, 

 is the presence of a parietal organ or parietal 

 eye in the roof of the cranium— a structure 



Figure 282. The green turtle Chelonia. A marine 

 species that has been so much hunted for food that 

 it may be in danger of extinction. Its fat is green 

 in color. The frontlimbs are flippers used for swim- 

 ming, and its hindlimbs are used as a steering ap- 

 paratus and as kickers. It weighs about 400 pounds. 

 (Courtesy of American Museum of Natural History.) 



with a retina and other characters resem- 

 bling a true eye in juveniles, but it is vestigial 

 in adults, and scarcely visible. 



Lizards 



elongated 



The lizards usually have an 

 body and 4 well-developed limbs for run- 

 ning, clinging, climbing, or digging. Some, 



for example the glass snakes, have no limbs 

 or only vestiges. The tail is generally long; it 

 is easily broken off, but in many a new organ 

 is soon regenerated which does not possess 



Figure 283. Tuatara [Sphenodon punctatus) at 

 the entrance of its burrow. It has characters of the 

 early ancestral reptiles. A relic of a remote past ("a 

 living fossil"), now found only on islands near New 

 Zealand. Length about two feet. (Photo by Blanch- 

 ard. (Courtesy of National Geographic Societv.) 



