REPTILIA 561 



the Old World they occur in tropical Africa, Southern Asia, Java, 

 Sumatra, and Northern Australia. 



In the United States two genera with one species each are found. 

 One, Alligator mississi'p'piensis , is found in all our coastal states from 

 the Kio Grande to the Carolinas. The other, Crocodilus acidus, is 

 found in the southern tip of Florida, ]\Iexico, Central and South 

 America. 



The general appearance of alligators is well known to everyone. 

 The animals are not covered by scales but are protected by rows 

 of dermal ossicles in the skin. Formerly a crocodile or an alligator 

 might be found that was as long as thirty feet, but it is doubtful 

 whether such an animal can be found today. 



The females lay eggs in a nest built of sticks and decaying vegeta- 

 tion. The heat generated by decomposing vegetable matter aids in 

 incubating the eggs. It was formerly thought that the growth of 

 alligators was very slow but specimens in captivity have been 

 brought to a length of five and one-half feet in five years. 



THE HORNED LIZARD 



The horned lizard is a convenient reptile to study since one or 

 more species is found locally throughout southwestern United States. 

 It is usually found in abundance and is relatively easy to capture. 

 The ''horns" on the head are unique among living reptiles. The 

 general plan of structure is sufficiently generalized to illustrate most 

 of the characteristics typical of reptiles. 



Habits and Behavior 



These lizards are diurnal animals, feeding by day and at night bur- 

 rowing into the ground until only their head spines can be seen. Their 

 food consists of small beetles, flies, smooth caterpillars, moths, ants, 

 and other small insects. The animals are solitary, not being found 

 in groups in dens. Each one burrows underground to hibernate 

 during the cooler season of the year. After mating, a female of 

 an oviparous species digs a cup-shaped hole and deposits twenty 

 to twenty-five eggs in it, covering the eggs with several layers of 

 earth. Females of the ovoviviparous species bring forth the young 

 alive. 



