34 



SEXUAL SELECTION. 



Part IL 



There are other and much more remarkable dif- 

 ferences between the sexes of certain lizards. The 

 male of Ceratoioliora aspera bears on the extremity of 

 his snout an appendage half as long as the head. It 

 is cylindrical, covered with scales, flexible, and appa- 

 rently capable of erection : in the female it is quite 

 rudimental. In a second species of the same genus a 

 terminal scale forms a minute horn on the summit 

 of the flexible appendage ; and in a third species {G. 

 Stoddartii, fig. 31) the whole appendage is converted 



into a horn, which is usually 

 of a white colour, but as- 

 sumes a purplish tint when 

 the animal is excited. In 

 the adult male of this latter 

 species the horn is half an 

 inch in length, but is of quite 

 minute size in the female and 

 in the young. These appen- 

 dages, as Dr. Giiuther has 

 remarked to me, mav be 

 compared with the combs of 

 gallinaceous birds, and appa- 

 ently serve as ornaments. 

 In the genus Chama3leon we come to the climax of 

 difference between the sexes. The upper part of the 

 skull of the male G. hifurcus (fig. 35), an inhabitant of 

 jMadagascar, is produced into two great, solid, bony pro- 

 jections, covered with scales like the rest of the head ; 

 and of this wonderful modification of structure the female 

 exhibits only a rudiment. Again, in Chameleon Owenii 

 (fig. 3 (J), from the West Coast of Africa, the male bears 



Fig. 34. Ceratophora Stoddartii. Upper 

 figure, male ; lower figure, female. 



taheu from Dr. Giinther's ma2:iiificeiit work on the ' Eeiitiles of British 

 India,' Kay Soc. 1SG4, p. 122, 130, 135. 



