PROBLEM I. The Kinds of Animals of the Earth 



27 



Fig. ^4 How Tiiciiiy ratllcs 

 has this rattlesnake'!' It is not 

 true that one can tell a rattle- 

 snake's age by the inanber of 

 rattles, (u. s. bureau of bio- 

 logical survey) 



Fig. 35 The head of a rattle- 

 snake ready to strike. Where 

 is the poison gland located 

 ■ivith relation to the fangs? 



Poison gland 



Poison duct 



Fang (foofhj 



alligators and crocodiles, and tuxtles. 



Our poisonous snakes. The feeling of 

 horror that snakes arouse in some people 

 is unreasonable. As a child you may 

 have seen your elders shrink at the sight 

 of a snake and you may have learned to 

 imitate them. Children left to them- 

 selves have no more fear of snakes than 

 of any other animals that seem strange. 

 Most snakes are harmless; poisonous 

 snakes are the exception. In this country 

 there are only four kinds of poisonous 

 snakes: the rattlesnake, the copperhead, 

 the water moccasin, and the coral snake. 

 On our continent man is rarely bitten, 

 even where poisonous snakes are nu- 

 merous, for with the exception of the 

 water moccasin our poisonous snakes 

 are timid; they do not attack unless they 

 are disturbed. Still more rarely does any 

 one die of the bite. An understanding of 

 the methods of treating a bite and the 



Gland-squeezing muscle 



'y- Jaw-opening 

 muscle 



courage to remain calm almost always 

 prevent serious results from the poison. 



The poison is injected through a pair 

 of large, hollow, very sharp fangs 

 (teeth). These are in the upper jaw, 

 folded back out of the way until the 

 snake strikes. The swiftly-moving little 

 tongue contains no poison; the snake 

 uses it to learn of its surroundings. 



Rattlesnakes are widely scattered over 

 the United States. When disturbed, they 

 sound their rattles, which are located at 

 the tip of the tail, so that it is easy to 

 avoid them. It is only when they are 

 taken by surprise that they strike with- 

 out warning. The amount of poison in- 

 jected depends on the size of the snake. 

 Large rattlers are therefore more dan- 

 gerous than small ones. The copperhead 

 is found in various regions in the north- 

 ern half of the country. The water 

 moccasin and the coral snake are not 



