272 VERTEBRATE ANIMALS. 
protected by movable eyelids, and the ear by a movable ear-lid. 
The tongue is large and fleshy, and is immovably attached to 
the bottom of the mouth (hence the belief of the ancients that 
the Crocodile had no tongue). Lastly, the Cvrocodilia agree 
with the typical Lizards, and differ from the Snakes in having 
four well-developed limbs. 
The Crocodi/ia abound in the fresh waters of hot climates, 
and are the largest of all living Reptiles, not uncommonly at- 
taining a length of sixteen feet or upwards. The best known 
of the Crocodilia is the Nilotic Crocodile (fig. 147), which occurs 
abundantly in Egypt, and was described by both Herodotus 
and Aristotle. 
The true Crocodiles have the feet completely webbed, the 
hind-legs bordered by a fringe, and the fourth tooth in the lower 
jaw received in a notch on the side of the upper jaw. They 
Fig. 147.—Head and fore-part of the body of the common Crocodile (Cvocodilus 
vulgaris). 
belong mainly to Africa and Asia, but they are also represented 
in the West Indies and in South America. 
The Alligators have the hind-legs simply rounded, and the 
toes not completely webbed ; while the fourth tooth in the lower 
jaw fits into a cavity in the palate, and is concealed from view 
when the mouth is shut. Like the Crocodiles, they are essen- 
tially aquatic in their habits, and lie dormant during the winter 
in cold climates and the hot season in warm countries. They 
are extremely voracious, and live upon fish and small Mammals. 
The best-known species are the common Alligator (4. A/Zsszs- 
stppiensis) of the Southern States, the Caiman (A. palpebrosus) 
of Surinam and Guiana, and the “‘ Jacaré” (A. sclerops) of South 
America. 
The Gavial or Gangetic Crocodile occurs in India, and is 
