462 



THE DESCENT OF MAN 



phora aspera bears on the extremity of his snout an append- 

 age half as long as the head. It is cylindrical, covered 

 with scales, flexible, and apparently 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 

 (C. Stoddartii, Fig. 84) the whole appendage is converted 

 into a horn, which is usually of a white color, but assumes 

 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 it is of quite minute size in the female and in the 

 young. These appendages, as Dr. Gunther has remarked 



to me, may be compared with the 

 combs of gallinaceous birds, and 

 apparently serve as ornaments. 



In the genus Chamaeleon we come 

 to the acme of difference between 

 the sexes. The upper part of the 

 skull of the male (C. bifurcus, Fig. 

 85), 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 rudi- 

 ment. Again, in Ohamodeon Owenii (Fig. 36), from the 

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

 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 with those of a bull, goat, or other sheath-horned 

 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 economy of these two animals. 

 The first conjecture, which will occur to every one, is that 



"K'-f 



Fict. 34.— Ceratophora Stod- 

 dartii. Upper fi^re, male; 

 lower figure, female. 



