SEVENTH ANNUAL REPORT. 158 
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 ring 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 number of joints of the rattle when that ap- 
pendage is ofa 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 usually about six feet. 
