6O2 OPHIDIA CHAP. 



and the New Hebrides. Casarea dussumieri is found on Round 

 Island near Mauritius ; and two species of Boa and one of Corallus 

 represent the Boidae in Madagascar, while all the others live in 

 Central and South America. 



Boa. The maxillary and mandibular teeth gradually decrease 

 in size. The scales of the upper parts of the body and tail are 

 smooth and very small. The rostral shield is enlarged. The 

 nostrils are placed between two or three nasals, and these are 

 separated from those of the other side by small scales. The tail 

 is short and prehensile. The pupil is vertical. 



B. constrictor, of South America, has the head covered with 

 small scales, one of the pre-oculars being enlarged. The eye is 

 separated from the labials by several series of tiny scales. The 

 general colour is a delicate " pale brown above, with fifteen to 

 twenty dark brown cross-bars widening on each side, and, if con- 

 nected by a dark dorso-lateral streak, enclosing large elongate 

 oval spots. ... On each side is a series of large dark brown spots 

 with light centres, most of which alternate with the cross-bars. 

 On the tail the markings become much larger, brick-red, edged 

 with black, and separated by narrow, yellowish interspaces." 

 Under parts yellowish with black dots. Boa constrictor, a name 

 applied in popular parlance to many species, reaches a length of 

 more than 1 feet ; the largest specimen in the British Museum 

 measures exactly 11 feet. A few other species inhabit Central 

 America and the West Indies. B. dumerili and B. madagas- 

 cariensis, both of Madagascar, cannot be separated from the genus 

 Boa. 



A. D. Bartlett 1 has described the following incident : 



" In the evening of 5th October 1892 two pigeons were put 

 into the cage in which two fine specimens of Boa constrictor had 

 been living on friendly terms since the beginning of the year. 

 The larger snake seized one of the pigeons and the keeper left 

 the house. The next morning only one of the snakes, the larger 

 specimen, was visible, and from its enormously extended body 

 it was evident that it had swallowed its companion, which was 

 about 9 feet in length. It had no longer the power of curling 

 itself round, but remained extended nearly to its full length in a 

 straight line, and appeared to be at least three times its normal 

 circumference. It was almost painful to see the distended skin, 



1 P.Z.S. 1894, p. 669. 



