786 DR. p. CHALMERS MITCHELL AND MR. R. I. POCOCK [NoV. 12, 



and the end of October 1907, We chose the summer months, 

 as even in a House artificially heated all snakes feed less readily 

 and some of them not at all during the winter months. 



General Observations. 



All our remarks under this heading relate to animals which 

 have been killed before being offered to the snakes. Movements 

 of the prey are movements that we have caused by variovis means, 

 by throwing the animals in suddenly, by wriggling them with 

 wooden forceps or attached twine, and so forth. We have not 

 noticed any difference in the readiness of the snakes to take food 

 if the animals were freshly killed, warm, or bleeding, or if they 

 had been dead for some time ; and it is to be noticed that, in many 

 cases the prey was not actually taken until night, long after it 

 had been introduced ; this was particularly the case when Pythons 

 took large animals such as goats. 



For the present purpose snakes may be divided into four 

 groups : — Pythons ; Non-poisonous Colubrines ; Poisonous Colu- 

 brines ; Yipers. 



Pythons. — Pythons and Anacondas generally show their readi- 

 ness to feed by special restlessness and activity; they move about 

 restlessly. Pythons often leaving their tanks completely and 

 Anacondas stretching part of the body out of the water ; they 

 become specially alert when they hear movements in the passage 

 behind their cages, or when the back-doors are moved ; in the 

 words of the keeper, " they are asking for food." But this is not 

 invariable ; sometimes a Python will take no notice when the 

 prey is thrown in or when it is moved in front of it or dangled 

 over it, and yet later on it will take it. If the snake is eagei-, it 

 makes a sudden dart at the prey, striking at no special part of 

 the body and seizing and retaining hold with a violent: bite. An 

 Anaconda taking hold of a duck in this way almost at the same 

 moment surrounds it with one or two tight coils and takes it 

 nnder water. A Python without letting go throws a coil over 

 it, holding it down ; if the prey is of small size and motionless 

 there is no attempt to wind the body round it, bvit if it is bulky 

 or moves more coils are pressed over- or round it. There appears, 

 however, to be no special attempt to crush the prey, to suffocate 

 it, or to break its bones. The amount of pressure or constriction 

 exerted is, so to speak, a reflex action directly proportioned to 

 the struggles or size of the prey. After some time, during which 

 an originally living prey would have been suffocated, or in the 

 case of the Anaconda drowned, the snake usually lets go its hold. 

 It then passes its head all round the prey, playing over it with 

 its forked tongue, and by some means other than that of sight, as 

 the choice is made equally in the dai-k, perhaps by the sense of 

 touch in the muzzle or lips, selects the head of the carcase to 

 begin the process of swallowing. A snake that comes across a 

 dead body behaves in the same way. We have never seen a snake 



