39° ZOOLOGY 



veloped than in the Amphibia. This is especially true of the 

 cerebral hemispheres. The usual senses are represented. The 

 rather large eyes are provided with movable eyelids except 

 among the snakes, in which a permanent transparent membrane 

 covers the eye. In some reptiles (lizards) there is a remnant 

 of a median eye which is very degenerate in the adult. It is in 

 connection with the pineal body in the second division of the 

 brain. Hearing varies. It is rather keen in turtles; apparently 

 less so in snakes. Smell is well developed. Touch is repre- 

 sented in the skin over the body, but is interfered with by the 

 scales and plates. 



421. Habits. — The reptiles are best represented in the 

 tropical regions. The larger types, as the crocodiles, python, 

 boa are almost confined to the warm zones, especially of South 

 America, Africa and Asia. Numerous smaller representatives 

 of the lizards, snakes, and turtles are found in temperate lati- 

 tudes. These usually undergo a period of hibernation during 

 the cold season. This habit of hibernating and seeking warmer 

 climates seems related to the cold-blooded condition. The heat- 

 producing qualities of the animals are not equal to the task of 

 maintaining activity during extreme cold. The variation of 

 temperature is of course a more serious problem to terrestrial 

 animals than to aquatic types. Although air-breathers, very 

 many of the group are aquatic, as the turtles, crocodiles, and 

 many snakes. The lizards are almost without exception terres- 

 trial. Nearly all prey on other animals; the smaller on worms, 

 insects, and eggs of various kinds, and the larger on birds, fish, 

 Amphibia, and mammals. The land tortoises are vegetable 

 feeders. 



Reptiles are rather sluggish animals. They like to bask in 

 the sun. They are capable often of very rapid motion; but it 

 is spasmodic. 



Reptiles, especially the snakes, have a bad reputation, yet 

 there is no doubt that their dangerous qualities are much ex- 

 aggerated in popular opinion. The lizards are almost wholly 

 non-venomous and the majority of the common snakes of this 

 country are also harmless. The principal dangerous snakes 



