306 REPTILES AND BATRACHIANS 



They are purely aquatic, and must be provided with a tank 

 suitable for swimming. Because of the non-resistant char- 

 acter of their covering, hard objects should not be placed 

 in the tank, a water-soaked bit of wood being sufficient for 

 them to crawl out upon. They should be fed on worms, 

 meat, cut fish and clams. 



The true tortoises have long forgotten their aquatic 

 habits, and their feet have become modified as an adapta- 

 tion to terrestrial life. The group includes the Giant Tor- 

 toises, which are exceeded in size only by the marine turtles, 

 and are believed to live a great number of years. The best 

 known American species is the Gopher Tortoise ( Testudo 

 Polyphemus), of the southern states. It is abundant in 

 sandy districts, living in burrows. Like most of the group, 

 it lives well in captivity, but is very sensitive to cold, the 

 least drop in temperature causing it to approach as closely as 

 possible to the source of heat in its quarters. It should be 

 fed on meat, and lettuce, tomatoes and other vegetables. 



