SEXUAL SELECTION 



463 



they are used by the males for fighting together; and, as 

 these animals are very quarrelsome," this is probably a 

 correct view. Mr. T. W. Wood also informs me that he 

 once watched two individuals of G. pumilus fighting vio- 

 lently on the branch of a tree; they flung their heads about 

 and tried to bite each other ; they, then rested for a time, 

 and afterward continued their battle. 



With many lizards, the sexes difiet slightly in color, 



;?!?« i ' 







PsB. 35.— OhamsBleon bifurcua. Upper figure, male; lower figure, female. 



the tints and stripes of the males being brighter and more 

 distinctly defined than in the females. This, for instance, 

 is the case with the above Oophotis and with the Acan- 

 ihodactylus capensis of South Africa. In a Cordylus of the 

 latter country, the male is either much redder or greener 

 than the female. In the Indian Calotes nigrilahris there is 



«' Dr. Bucholz, "Monatsbericht K. Preusa Akad.," Jan. 1874, p. t8. 



