460 THE DESCENT OF MAN 



the surrounding stalks of plants; and I have myself heard 

 this in the case of a Trigonooephalus in South America. 



Lacertilia. — The males of some, probably of many, kinds 

 of lizards fight together from rivalry. Thus the arboreal 

 Anolis cristatellus of South America is extremely pugna- 

 cious: "During the spring and early part of the summer, 

 two adult males rarely meet without a contest. On first 

 seeing one another, they nod their heads up and down 

 three or four times, and at the same time expanding the 

 frill or pouch beneath the throat; their eyes glisten with 

 rage, and after waving their tails from side to side for a 

 few seconds, 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 com- 

 batants 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. Grunther has been 

 able to ascertain, is the general rule with lizards of all 

 kinds. The male alone of the Gyrtodactylus ruhidus of 

 the Andaman Islands possesses pre-anal pores; and these 

 pores, judging from analogy, probably serve to emit aa 

 odor.°° 



The sexes often differ greatly in various external char- 

 acters. The male of the above-mentioned Anolis is fur- 

 nished with a crest which runs along the back and tail, 

 and can be erected at pleasure; but of this crest the female 

 does not exhibit a trace. In the Indian Gophotis 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 de- 

 veloped in both sexes, as in the Iguana tuherculata. In the 

 genus Sitana, the males alone are furnished with a large 

 throat-pouch (Fig. 33), which can be folded up like a fan, 



«6 Mr. N. L. Austen kept these animals alive for a considerable time; sea 

 "Land and Water," July, 1861, p. 9. 



«* Stoliozira, "Journal of Asiatic Soc. of Bengal," vol. xxxiv., 1810, p. 166. 



