30 
SEXUAL SELECTION. 
Part IL 
In the Tragojps dispar of the same country, the male is 
bright green, and the female bronze-coloured.^^ No 
doubt the colours of some snakes serve as a protection^ 
as the green tints of tree-snakes and the various mottled 
shades of the species which live in sandy places; but 
it is doubtful whether the colours of many kinds, for 
instance of the common English snake or viper, serve 
to conceal them ; and this is still more doubtful with 
the many foreign species which are coloured with ex- 
treme elegance. 
During the breeding-season their anal scent-glands 
are in active function and so it is with the same 
glands in lizards, and as we have seen with the sub- 
maxillary glands of crocodiles. As the males of most 
animals search for the females, these odoriferous glands 
probably serve to excite or charm the female, rather 
than to guide her to the spot where the male may be 
found.^^ Male snakes, though appearing so sluggish, 
are amorous ; for many have been observed crowding 
round the same female, and even round the dead body 
of a female. They are not known to fight together 
from rivalry. Their intellectual powers are higher than 
might have been anticipated. An excellent observer 
in Ceylon, Mr. E. Layard,^^ saw a Cobra thrust its head 
through a narrow hole and swallow a toad. ^^Witli 
Dr. A. Gunther, ‘ Keptiles of British India,’ Kay Soc. 1864, p. 
304, 308. 
Owen, ^ Anatomy of Vertebrates,’ vol. i. 1866, p. 615. 
^2 The celebrated botanist Schleiden incidently remarks (‘Ueber 
den Darwinismus : Unsere Zeit,’ 1869, s. 269), that Kattle-snakes use 
their rattles as a sexual call, by which the two sexes find each other. 
I do not know whether this suggestion rests on any direct observations. 
These snakes pair in the Zoological Gardens, but the keepers have 
never observed that they use their rattles at this season more than at 
any other. 
“ Kambles in Ceylon,” ‘ Annals and Mag. of Nat. Hist.’ 2nd series, 
vol. ix. 1852, p. 333. 
