306 VERTEBRATES : REPTILES. 



bites, the fangs are raised, and the pressure of the tem- 

 poral muscles upon the gland forces the poison along the 

 fang into the wound. These animals have a deep pit 

 between the eye and the nostril, and the rattlesnakes 

 proper have the tail furnished with a rattle, with which 

 they make a peculiar noise when they apprehend danger. 



The Genus Crotahis comprises the Rattlesnakes proper. 

 Several species are found in the United States. 



The Common Rattlesnake, C. durissus, Linn., is three 

 to four feet long, sulphur brown above, with two rows of 

 confluent, lozenge-shaped brown spots ; tail black. It 

 is generally sluggish, and never attacks animals unless 

 disturbed or hungry. But the slightest noise will arouse 

 it, when it immediately coils, moves the rattles violently, 

 and strikes at whatever comes within reach. It never 

 pursues the object of its anger, but strikes on the spot, 

 and, recoiling, repeats the blow as often as it can. This 

 snake feeds upon young hares, squirrels, and birds, which 

 it secures by lying in wait for them. Its reported charm- 

 ing power is probably a mere notion which has no foun- 

 dation in fact. It was formerly supposed that the num- 

 ber of rattles indicates the age, one rattle being added 

 each year ; but this is not so. In some cases there are 

 more than one added in a year, and in others, one or 

 more is lost. 



The Diamond Rattlesnake, C. adamanteus, Beauv., of 

 Carolina and southward, attains the length of eight feet. 



The Genus Crotalophorus has the tail with a rattle, and 

 top of the head covered with plates, as in Coluber. Five 

 species are stated to be found in the United States. 



The Prairie Rattlesnake, or Massasauga, C. tergeminus, 

 Holbr., of the Prairies, is twenty to thirty inches long. 



The Genus Ancistrodon has the tail without a rattle, 

 and loral plates present. 



The Copperhead, A. contortrix, B. & G., of the Southern 



