PUFF ADDERS IN CAPTIVITY. 223 



October in this district, and it would be about this time or a 

 little later that impregnation of the female would take place. 



I have noticed that captive Puff Adders are active in the 

 pursuit of the females in October, November, and December, 

 and that during the autumn they show no inclination. 



Young Puff Adders will live in apparent health for as long as 

 three months after birth without food. They also grow larger 

 in girth and increase in length sometimes by as much as two 

 inches. I have noticed this on several occasions. I have at 

 present a batch under observation. They refuse all food. It is 

 now two months since they were born, and yet they do not show 

 any signs of emaciation. Some have increased half an inch, 

 others up to one and a half inches in length. All are slightly 

 larger in girth than when born. 



On the 24th June, 191 1, I captured a large female Puff Adder, 

 which appeared to be gravid. I killed the reptile, and, on opening 

 it, found eleven fully-developed eggs lying in a row along one 

 side of the backbone and sixteen on the other. I carefully 

 examined these eggs, but could not find the slightest signs of an 

 embryo. Whether they were impregnated or not I cannot say. 

 June is mid-winter in South Africa, and if these eggs were im- 

 pregnated then it must have occurred during the previous 

 autumn, as this snake was hibernating when I secured it. 



In July another large female Puff Adder was captured, which, 

 when killed and opened was found to contain twenty-four fully- 

 developed eggs. They lay in two equal rows on each side of the 

 backbone. There was a good deal of fat in flaky masses covering 

 the eggs, although the winter was well advanced. There were 

 no signs at all of the eggs having been impregnated. It seems 

 to me to be very likely that at least in the case of Puff Adders, 

 the eggs develop during the period of hibernation, as snakes are 

 nvariably very fat and in excellent condition late in the autumn. 

 Then, when the female issues forth in the spring, she is im- 

 pregnated by the male, and the eggs forthwith begin to incubate. 

 I have found that Puff Adders always give birth to their young 

 in the autumn. Subsequent observations have confirmed this. 



Puff Adders in Captivity. 

 These snakes in captivity thrive if kept in natural conditions, 

 but unless they have plenty of sunshine, and the temperature of 



