love, a musky odour is emitted by the submaxillary glands of the
crocodile, and pervades their haunts. (55. Owen, Anatomy of
Vertebrates, vol. i. 1866, p. 615.)
OPHIDIA.
Dr. Gunther informs me that the males are always smaller than the
females, and generally have longer and slenderer tails; but he knows of
no other difference in external structure. In regard to colour, be can
almost always distinguish the male from the female, by his more
strongly-pronounced tints; thus the black zigzag band on the back of
the male English viper is more distinctly defined than in the female.
The difference is much plainer in the rattle-snakes of N. America, the
male of which, as the keeper in the Zoological Gardens shewed me, can
at once be distinguished from the female by having more lurid yellow
about its whole body. In S. Africa the Bucephalus capensis presents an
analogous difference, for the female is never so fully variegated with
yellow on the sides as the male. (56. Sir Andrew Smith, Zoology of S.
Africa: Reptilia, 1849, pl. x.) The male of the Indian Dipsas cynodon,
on the other hand, is blackish-brown, with the belly partly black,
whilst the female is reddish or yellowish-olive, with the belly either
uniform yellowish or marbled with black. In the Tragops dispar of the
same country the male is bright green, and the female bronze-coloured.
(57. Dr. A. Gunther, Reptiles of British India, Ray Soc., 1864, pp.
304, 308.) No doubt the colours of some snakes are protective, as shewn
by 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 and
viper, serve to conceal them; and this is still more doubtful with the
many foreign species which are coloured with extreme elegance. The
colours of certain species are very different in the adult and young
states. (58. Dr. Stoliczka, Journal of Asiatic Society of Bengal,
vol. xxxix, 1870, pp. 205, 211.)
During the breeding-season the anal scent-glands of snakes are in
active function (59. Owen, Anatomy of Vertebrates, vol. i. 1866, p.
615.); and so it is with the same glands in lizards, and as we have
seen with the submaxillary 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
380