36 
SEXUAL SELECTION. 
Part II. 
first conjecture which will occur to every one is that 
they are used by the males for fighting together ; but 
Dr. Gunther, to whom I am indebted for the foregoing 
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 slightly in co- 
lour, the tints and 
stripes of the males 
being brighter and 
more distinctly de- 
fined than in the 
Fig. 36. Cbamaileon Owenii. Upper figure, male ; TLIa 
lower figure, female. lemaies. ±U1S, lOi 
instance, is the case 
with the previously-mentioned Cophotis and with the 
Acantliodactylus capensis of S. Africa. In a Cordylus 
of the latter country, the male is either much redder or 
greener than the female. In the Indian Galotes nigri- 
Idbris 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 vivipara) “the 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 
Bell, ‘History of British Kep tiles,’ 2ncl edit. 1849, p. 40. 
