36 



SEXUAL SELECTION. 



Part IL 



first conjecture wliicb will occur to every one is that 

 thev are used bv the males for fiHitino- tosfether ; but 

 Dr. Giinther, to whom I am indebted lor the fores-oinof 

 details, does not believe that such peacable crea- 

 tures would ever become pugnacious. Hence we are 



driven to infer that 

 these almost mon- 

 strous deviations 

 of structure serve 

 as masculine orna- 

 ments. 



With many kinds 

 of lizards, the sexes 

 differ sliohtlv in co- 

 lour, the tints and 

 stripes of the males 

 being brighter and 

 more distinctly de- 

 fined than in the 

 females. This, for 

 instance, is the case 

 ^vith the previously-mentioned Cophotis and with the 

 Acantliodadylus capensis of S. Africa. In a Cordylus 

 of the latter countrv, the male is either much redder or 

 greener than the female. In the Indian Calotes nigri- 

 lahris there is a greater difference in colour between 

 the sexes ; the lips also of the male are black, whilst 

 those of the female are green. In our common 

 little viviparous lizard (Zootoca vivijoara) *Hhe under 

 '• side of the body and base of the tail in the male are 

 " bright orange, spotted with black; in the female 

 " these parts are pale greyish-green without spots." ^" 

 We have seen that the males alone of Sitana possess a 



Fig. 36. Chameleon Owenii. Upper figure, male ; 

 lower figure, female. 



57 



Bell, ' History of British Eeptiles,' 2nd edit. 1849, p. 40. 



