CLASS REPTILIA 



425 



Figure 298. The coral snake, a very poisonous 

 snake, which hves in southern United States and 

 the tropical countries. It is the only representative 

 of the cobra family in North America. It is about 

 three feet long. (Courtesy of N.Y. Zoological So- 

 ciety. ) 



held in resewe to replace those that are lost 

 in struggles with prey or are normally shed. 

 Rattlesnakes are most abundant both in re- 

 gard to the number of species and the num- 



ber of individuals in the deserts of the south- 

 western United States, but almost every part 

 of this country is inhabited by one or more 

 species. 



The rattlesnake is one of the so-called pit 

 vipers because it has a pit between the eye 

 and nostril on each side of the head. In this 

 pit is located the pit organ w^hich consists 

 of highly vascular tissue and many nerve 

 endings. Experiments prove that this is a 

 heat-sensitive organ; a rattlesnake can detect 

 the movement of a moderately warm body 

 passing its head at a distance of several feet. 

 Obviously this sense is very useful to an 

 animal which lives to a considerable extent 

 on warm-blooded rodents. 



Rattlesnakes and other pit vipers usually 

 strike from an S-shaped position of the body. 

 Unless the venom is injected directly into a 

 blood vessel, it usually travels slowly. The 

 best first-aid measures to take in the case of a 

 snake bite are: (1) apply a ligature or 

 tourniquet a few inches above the bite— a 

 rubber garter, handkerchief, cord, or even a 

 shoestring will do; about every 15 minutes 



Figure 299. Water moccasin (cotton-mouth) snake about to strike. Its bite is occasionally 

 fatal to man. Note the thick body, slender neck, and whitish mouth; it has a pit in front of 

 the eye. It lives in or near water. (Courtesy of N.Y. Zoological Society.) 



