Chap. XII. 
KEPTILES. 
37 
throat-poucli ; and this is splendidly tinted with blue, 
black, and red. In the Froctotretus 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 Froctotretus which 
closely resembles the sand on which it lives. On the 
whole Ave may conclude with tolerable safety that the 
beautiful colours of many lizards, as Avell 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 Avith 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 Froctotretus see 'Zoology of the Voyage of the ‘‘ Beagle 
Eeptiles,’ by Mr. Bell, p. 8. For the Lizards of S. Africa, see ‘Zoology 
of S. Africa: Eeptiles,’ by Sir Andrew Smith, pi. 25 and 89. For the 
Indian Calotes, see ‘Eeptiles of British India,’ by Dr. Gunther, p. 148. 
