206 Descriptive Zoology. 



ashore to lay their eggs. Among the more noticeable of 

 our inland turtles are the fierce snapping turtle, the soft- 

 shell turtle, and the " gopher " of the South, which burrows 

 in the ground. The terrapins of Chesapeake Bay are 

 noted for their quality as food. All turtles bury their eggs, 

 and our northern forms all hibernate in the mud. 



THE ALLIGATORS. 



General Features. The alligators and crocodiles are 

 like lizards in general form, but differ from them in several 

 important points. They swim well by means of the verti- 

 cally flattened tail. The skin is covered with horny 

 scales, those of the back having corresponding underlying 

 bony plates. The teeth of alligators are set in sockets, 

 which is true of no animals below it in scale. The heart 

 is also more complete than in the other reptiles, having a 

 complete partition separating the ventricle into two parts. 

 The temperature is about that of the surrounding air or 

 water. The brain, though more highly developed than in 

 other reptiles, is small relative to the size of the body and 

 the skull. The alligators have a muscular, gizzardlike 

 stomach. The young feed on fishes and small animals, 

 but the full-grown alligators seize mammals, for which they 

 lie in wait at the edge of the water until the animals come 

 down to drink or swim. The nostrils, eyes, and ears are 

 at the top of the head, so these reptiles can lie concealed, 

 with their main sense organs extending into the air to 

 discover their prey ; they very much resemble a stranded 

 log. The nostrils can be closed by a valve, which is 

 done when a victim is dragged under water to drown. 

 Alligators dig holes in the banks, in which they lay their 

 eggs, which are sometimes as large as those of a goose. 



The alligators of our Southern states grow to a length of 



