352 THE DESCENT OF MAN. 



In the genus ChamaBleon we come to the acme of difference be- 

 tween the sexes. The upper part of the skull of the male C. bifurcus 

 (fig. 35), an inhabitant of Madagascar, is produced into two great, 

 solid, bony projections, covered with scales like the rest of the 

 head; and of this wonderful modification of structure the female 

 exhibits only a rudiment. Again, in Chamseleon Owenii (fig. 36), 

 from the "West Coast of Africa, the male bears on his snout and 



Pig. 35. Chamaeleon bifurcus. Upper figure, male; lower figure, female. 



forehead three curious horns, of which ,the female has not a trace. 

 These horns consist of an excrescence of bone covered with a 

 smooth sheath, forming part of the general integuments of the 

 body, so that they are identical in structure v/ith those of a bull, 

 goat, or other sheathhorned ruminant. Although the three horns 

 differ so much in appearance from the two great prolongations of 

 the skull in C. bifurcus, we can hardly doubt that they serve the 

 same general purpose in the econoiny of these two animals. The 



