TURTLES, TERRAPINS, AND TORTOISES ii 



available for examination in the case of living specimens, 

 we shall confine ourselves to the disposition and nomen- 

 clature of the latter, for v^^hich the reader is referred to 

 fig. 2. 



In some tortoises and terrapins perfect hinges of elastic 



Fig. 2. — Shell of Chelone mydas. 



f' 



ligament are formed across the plastron, as in the so-called 

 Box Tortoises, and either the anterior or the posterior 

 lobes, or both, as the case may be, are movable and close 

 up the shell. In the genus Cinixys a similar hinge is 

 situated across the carapace, the hinder part of which is 

 movable. 



