Chap. XII. REPTILES. 37 



throat-poucli ; and this is splendidly tinted with blue, 

 black, and red. In the Prodotretus tenuis of Chile the 

 male alone is marked with spots of blue, green, and 

 coppery-red.^^ I collected in S. America fourteen 

 species of this genus, and though I neglected to record 

 the sexes, I observed that certain individuals alone were 

 marked with emerald-like green spots, whilst others 

 had orange-coloured gorges ; and these in both cases 

 no doubt were the males. 



In the foregoing species, the males are more brightly 

 coloured than the females, but with many lizards both 

 sexes are coloured in the same elegant or even magni- 

 ficent manner ; and there is no reason to suppose that 

 such conspicuous colours are protective. With some 

 lizards, however, the green tints no doubt serve for 

 concealment ; and an instance has already been inci- 

 dently given of one species of Proctotretus which 

 closely resembles the sand on Avhich it lives. On the 

 whole we may conclude with tolerable safety that the 

 beautiful colours of many lizards, as well as various 

 appendages and other strange modifications of structure, 

 have been gained by the males through sexual selection 

 for the sake of ornament, and have been transmitted 

 either to their male offspring alone or to both sexes. 

 Sexual selection, indeed, seems to have played almost as 

 important a part with reptiles as with birds. But the 

 less conspicuous colours of the females in comparison 

 with those of the males cannot be accounted for, as 

 Mr. Wallace believes to be the case -with birds, by the 

 exposure of the females to danger during incubation. 



^^ For Proctotretus see ^ Zoology of the Voyage of the " Beagle : " 

 Keptiles,' by Mr. Bell, p. 8. For the Lizards of S. Africa, see ' Zoology 

 of S. Africa : Keptiles,' by Sir Andrew Smith, pi. 25 and 89. For the 

 Indian Calotes, &ee 'Keptiles of British India,' by Dr. Giinther, p. 143. 



