SEXUAL COLORATION. 257 



Among lizards and snakes sexual differences in coloration 

 exist, though instances of this dimorphism are not plentiful. 

 Lacerta galloti, of which there are at present a number of 

 specimens in the reptile house at the Zoological Gardens, 

 shows a dimorphism in colour, the throat of the male being of 

 a beautiful blue colour. The common British lizard (Zootoca 

 ''tr'tparot) shows a somewhat similar variation in the two 



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Fig. 29. Bird of Paradise. 



sexes : the under side is of a crimson tint in the male, and 

 pale buff in the female. 



Among snakes the Puff Adder (Vipera arietans) is an 

 instance in point. So different in colour are the two sexes 

 that they might readily be mistaken for two different kinds 

 of snakes. In the male the prevailing tint is a rich yellow- 

 brown, in the female the prevailing tint is grey. It would, how- 

 ever, be difficult to decide which of the two sexes has the more 



17 



