BOINAE 



603 



which had separated the scales all over the middle of the body. 

 By 2iid November, twenty-eight days later, the snake had not 

 only digested its companion but had regained its appetite as well 

 as its normal size, and it immediately swallowed a pigeon pnt 

 into its den." 



This peculiar case is not one of ordinary cannibalism. It is 

 rather an unintentional accident. When two snakes happen to get 

 hold of the same animal (in the present case a pigeon) and begin 

 to swallow it, the action of swallowing becomes almost mechanical, 

 the snakes continuing to push their jaws over the prey — which 

 in the case of a bird or mammal they cannot . taste, nor can they 

 see it — so long as they feel something in the mouth. After the 

 original prey has been mastered, it is the turn of the opposite 



Fig. 159. — Head of Eunedes murinus. 



snake's head, and if the weaker snake does not give way it is 

 swallowed by its stronger mate. Grass -Snakes will swallow 

 several frogs if these are tied together in a string, and other 

 snakes do the same with mice. There are instances on record 

 in which a Python swallowed its Ijlanket, which, being absolutely 

 indigestible, caused its death. 



Casarea, the " Eound-Island Snake," differs from Boa chiefly 

 liy the rough and strongly keeled scales, and by the relatively 

 much longer tail. 



Eunectes murimis, the " Anaconda," is an aquatic Boa. It 

 differs from this genus mainly by the inner of the three nasal 

 shields being in contact with that of the other side (see Fig. 

 159), and by the absence of the little scales between the eye and 

 the labials ; the snout is, moreover, covered with shields instead 

 of small scales. The pupil of the eye is normally vertical, but it 

 had contracted into a round pinhole in the dead but still fresh 



