Photo by W. Saville-Kent.
THE BEARDED LIZARD.
Paring moments of excitement the Bearded Lizard opens the mouth widely displaying a vividly coloured interior.
[Face page 166
Normally sluggish, the Lizards display, it will have been remarked, a quite surprising degree of animation when maddened by mate-hunger. Some exhibit a considerable degree of pugnacity. In Anolis carolinensis, for example, when two males meet they face one another, bob the head up and down two or three times, expand the throat pouch, lash their tails from side to side, and then, worked up to the requisite degree of fury, rush at one another, rolling over and over and holding firmly with the teeth. The conflict generally ends in one of the combatants losing his tail, which is eaten by the victor.
The Chamæleons include among their number species which have developed quite formidable horns, recalling those of the Rhinoceros or, better, of the extinct Arsinoetherium, since they are placed side by side instead of one behind the other. In Owen’s Chamæleon there are three such horns, two on the forehead and a median horn on the snout, and these are borne only by the males.
The marvellous play of colour which many Lizards display is commonly attributed indifferently to “protective coloration” and to “sexual selection.” It is unlikely that both have played equally important parts in their development. If the case of certain of the Geckoes alone is taken, then there would seem to be no doubt but that “Natural Selection” was the agent which had determined their elaborations for protective purposes, and in such and similar cases this may be largely true. But the material which “Natural Selection” has worked upon has been furnished by the secretions of the sexual glands to which reference has so frequently been made already. These seem to possess a very marked tendency to contain an excitant which promotes the formation of intense pigmentation, or an excess of tissue which may assume the form of weapons of offence, or of excrescences in the form of spines, or other ornamental features. Animals in whom this tendency to pigmentation and ornament has developed must, so to speak, obtain a licence from “Natural Selection” if they are to retain it. That is to say, if such ornament whenever it appears makes the wearer conspicuous to its enemies, or hampers it in escaping therefrom, or in fulfilling the ordinary avocations of life, then its further progress will be inhibited, or the wearer will be exterminated. But the tendency to produce colour, a by-product of the sexual gland secretions, may incidentally serve to afford it a protective garb, and in this event its further elaboration in the required direction is assured.
In certain abnormal, sexually poisoned individuals among the human race it is well known pleasure is derived from flagellation. There is but one instance known to me where this obtains as a normal accompaniment of desire among the lower animals, and this occurs in one of the Painted Terrapins (Chrysemys picta), whose finger-nails are produced into long, whip-like ends. I had the good fortune to witness their use one day when in the Reptile House at the Zoological Gardens in London.
The unusual activity of a male of this species was the first thing to attract attention to his movements. Watched more closely, he was found to be dodging a female and making frantic efforts to swim round so as to oppose her path. This done, he closed up and immediately commenced to apply the bastinado to her head. The movements were so rapid that nothing more than a blurred image of these strange whips was visible. As soon as she escaped his attentions, he set about circumventing her again, and again succeeded: and this most extraordinary performance was repeated many times during my watch.