350 THE DESCENT OF MAN. 



"out a contest. On first seeing one another, they nod their heads 

 "up and down three or four times, and at the same time expand- 

 "ing the frill or pouch beneath the throat; their eyes glisten with 

 "rage, and after waving their tails from side to side for a few sec- 

 "onds, as if to gather energy, they dart at each other furiously, 

 "rolling over and over, and holding firmly with their teeth. The 

 "conflict generally ends in one of the combatants losing his tail, 

 "which is often devoured by the victor." The male of this species 

 is considerably larger than the female ;°= and this, as far as Dr. 

 Giinther has been able to ascertain, is the general rule with lizards 

 of all kinds. The males alone of the Cyrtodactylus rubidus of the 

 Andaman Islands possesses pre -anal pores; and these pores judg- 

 ing from analogy probably serve to emit an odor.™ 



The sexes often differ greatly in various external characters. 

 The male of the above-mentioned Anolis is furnished with a crest 

 which runs along the back and tail, and can be erected at pleas- 

 ure; but of this crest the female does not exhibit a trace. In the 

 Indian Cophotis ceylanica, the female has a dorsal crest, though 

 much less developed than in the male; and so it is, as Dr. Gunther 

 informs me, with the females of many Iguanas, Chameleons, and 

 other lizards. In some species, however, the crest is equally 

 developed in both sexes, as in the Iguana tuberculata. In the 

 genus Sitana, the males alone are furnished with a large throat- 

 pouch (fig. 33), which can be folded up like a fan, and is colored 

 blue, black, and red; but these splendid colors are exhibited only 

 during the pairing-season. The female does not possess even a 

 rudiment of this appendage. In the Anolis cristatellus, accord- 

 ing to Mr. Austen, the throat pouch, which is bright red marbled 

 with yellow, is present in the female, though in a rudimental con- 

 dition. Again, in certain other lizards, both sexes are equally 

 well provided with throat pouches. Here we see with species be- 

 longing to the same group, as in so many previous cases, the 

 same character either confined to the males, or more largely de- 

 veloped in them than in the females, or again equally developed 

 in both sexes. The little lizards of the genus Draco, which glide 

 through the air on their rib-supported parachutes, and which in 

 the beauty of their colors bafile description, are furnished with 

 skinny appendages to the throat "like the wattles of gallinaceous 

 birds." These become erected when the animal is excited. They 

 occur in both sexes, but are best developed when the male arrives 

 at maturity, at which age the middle appendage is sometimes 

 twice as long as the head. Most of the species likewise have a low 



" Mr. N. L. Austen kept these animals alive for a considerable time; 

 see 'Land and Water,' July, 1867, p. 9. 

 «» Stoliczka, 'Journal of Asiatic Soc. of Bengal,' vol. xxxiv. 1870, p. 166. 



