114 REPTILES AND BATRACHIANS 



differs from that of Mr. Ridley and of Prof. Vaillant, the 

 Boas and Pythons in the London Zoological Gardens, 

 big and small, feeding on the average once a fortnight 

 during the summer, and about once a month during the 

 winter. As may be observed, a Python, twenty-two feet 

 in length, fed on as many as thirty occasions in the course 

 of a year, while an adult Boa fed on thirty-five occasions. 



Unless disturbed, in confinement at least, these snakes 

 are very lethargic, seldom moving during the daytime, 

 when their elliptic pupils are so contracted as to be 

 almost invisible ; at night they become more active, and 

 climb the trees in their cages with some activity. 



All Pythons lay eggs, which are incubated by the 

 mother, while the Boas, without exception, bring forth 

 their young alive. 



In the true Pythons, genus Python, restricted to the Old 

 World, the head is elongate and flat ; the nostrils are 

 situated between two shields only, which are unequal in 

 size ; the shield capping the end of the snout and the 

 shields on both lips are deeply pitted. 



Pythons are found in the tropical parts of Africa, Asia, 

 the East Indian Archipelago, and Australia. They are 

 all expert both in swimming and climbing, and are gener- 

 ally to be found on the lower branches of trees in the 

 ' neighbourhood of water. 



Various species of Pythons have bred in captivity. The 

 eggs, which number from fifty to one hundred, are in 

 all cases protected, the mother coiling herself round 

 them, supplying the necessary heat for their incubation. 

 The following notes refer to the temperature during the 

 incubation of the eggs of a pair of large African Pythons 

 {P. sebce), which bred in our gardens some years ago, 



