BOINAE XENOPELTIDAE 605 



ground over which the snake creeps. Some specimens live on 

 lizards, others prefer mice. The prey is caught by the head, and 

 further secured by several turns of the body of the captor, whose 

 tail is then turned forwards, round the head of the victim, so 

 as to form a kind of knot. 



Not less striking than their agility is their jealousy, which 

 is so strong that a snake will occasionally leave the mouse 

 which it has just strangled in order to seize another snake's 

 mouse. Sometimes several snakes fight for the same mouse, 

 coiled together into one inextricable lump so that the mouse 

 itself is quite invisible. The snakes poke their heads about 

 in search of the hidden prey, and every attempt of one of 

 the snakes to free itself, causes the others to squeeze it firmer and 

 firmer, thinking apparently that the motion was caused by the 

 lost prey. 



Occasionally one of Werner's captives caught several mice 

 in succession. With these it crawled into a corner, dropped the 

 mice, and then proceeded quietly to swallow one after another. 

 After a fortnight the whole repast was digested, and the snake 

 was ready for more. 



Fam. 6. Xenopeltidae. — The single species, Xenopeltis uni- 

 color, of South -Eastern Asia, including the Malay Islands, has 

 been raised to the dignity of family -rank on account of the 

 ■ following combination of characters. The prefrontal bones are 

 still in contact with the nasals as in the previous families, but 

 the coronoid bones of the mandibles are absent as in the remain- 

 ing families. The whole suspensorial apparatus and the lower 

 jaw itself are peculiar. The dentary bone is movably attached 

 to the end of the much-elongated articular bone, the movability 

 being enhanced by the absence of the coronoid element.^ The 

 quadrate is short and thick, and is carried by the short and 

 broad squamosal, which lies flat against the skull, resembling in 

 this respect that of some of the Ilysiidae. Boulenger rightly 

 considers JCcncqielfis to be in various ways intermediate between 

 this family, the Boidae and the Colubridae. The head is small 

 and not distinct from the neck. The eyes are small and have 

 a vertical pupil. The body is cylindrical, covered above with 



1 The same arrangement occurs in the Colubrine genus Folyodontophis, with 

 about ten species in South-Eastern Asia, Madagascar, the Comoro Islands, and in 

 Central America. 



