270 PHII^OSOPHY OF ZOOLOGY. 



heat of the sun. The young are perfect at birth. The 

 testudinal reptiles furnish the navigators of the tropical 

 seas with wholesome and refreshing food, and are held in 

 high estimation by epicures in general. 



A. Lips corneous. 



Entrance to the cavity formed by the two plates closed 

 by a lid. 



1. CiSTUDA. Box tortoise. Back-plate emargmate 

 in front, with two notches behind. 



The lid is formed by a plate, having a cartilaginous joint, 

 and gives full protection to the members of the animal, when 

 withdrawn into die cavity. Cuvieh subdivides this genus 

 into such as have two lids, one to each aperture of the 

 shield, and such as have only one at the opening for the 

 head. 



Entrance without a lid. 



a. Breast-plate continuously solid. 



Head and feet capable of being withdrawn into the 

 shield. The back -plate is rounded, and divided into compart- 

 ments by large scales. Fore feet with five, and the hind 

 feet Avlth four, toes. Those of the first genus live on the 

 land, those of the second frequent fresh water. 



2. Testudo. Toes united and covered with a common 

 scaly skin. T. GrcEca. 



3. Emys. Toes webbed. Claws long. Testudo Eu- 



Extremities incapable of being withdrawn into the shield. 



4. Chelonura. Tail about the length of the shield. 

 Back-plate carinated, with sharp processes behind. Testu- 

 do serpentina. 



h. Breast-plate interrupted by intervening cartilaginous 

 spaces. Tl\e extremities are incapable of being withdrawn in- 



