SEVENTH ANNUAL REPORT. 153 



appears on the tail at the base of the rattle. This indicates the 

 position of a new ring, or joint. When the epidermis is shed, 

 this rin^- is uncovered. It is black and hard, and does not become 

 dry and brittle, nor of the color of the other joints of the rattle, 

 until it has been pushed from the tail by a succeeding joint. 



As a snake in its wild state sheds its skin about three times 

 during the warm months, the same number of rattles should be 

 added during the year. To determine the age of a rattlesnake 

 from the number of joints of its rattle is a very uncertain propo- 

 sition. When the rattle has attained from ten to twelve joints, it 

 usually remains at about that number, as several joints are lost 

 annually through wear. It is only possible to estimate the age 

 of a snake from the nuni])er of joints of the rattle when that ap- 

 pendage is of a tapering character and still possesses the "button" 

 of the snake's birth. The growth of the snake is indicated by 

 such a rattle in the increasing size of each ring from the button 

 to the tail. By allowing three rattles for a year, the reptile's age 

 may be determined with reasonable accuracy. When a snake's 

 rattle possesses all the joints or rings of a uniform size, the snake 

 is old. The tapering portion of the rattle grown in its youth has 

 been lost, together with an uncertain number of succeeding joints, 

 and the snake has ceased to grow. 



These snakes are unable to produce any sound with the rattle 

 until they are about three months old. By that time one skin 

 has been cast, a new joint uncovered on which is attached the 

 "button" of birth, and a second joint has developed to such an 

 extent that the one preceding it has become dry and brittle. On 

 the latter, the "button" whirs feebly when the tail is vibrated. 

 In the Reptile House a specimen of the Diamond-Backed Rattle- 

 snake, now fifteen months old, and born in the building, possesses 

 "five rattles," or "four rings," and a "button." This snake meas- 

 ured fourteen inches at birth. At the present time it measures 

 three feet, six inches. The length of a full-grown Diamond- 

 Backed Rattlesnake is usuallv about six feet. 



