SEXUAL SELECTION 649 



point of another jammed into the broken place."* The 

 tooth on the opposite side of the head in the male con- 

 sists of a rudiment about ten inches in length, which is 

 imbedded in the jaw; but sometimes, though rarely, both 

 are equally developed on the two sides. In the female 

 both are always rudimentary. The male cachalot has a 

 larger head than that of the female, and it no doubt aids 

 him in his aquatic battles. Lastly, the adult male ornitho- 

 rhynchus is provided with a remarkable apparatus, namely, 

 a spur on the foreleg, closely resembling the poison fang of 

 a venomous snake ; but according to Harting, the secretion 

 from the gland is not poisonous; and on the leg of the 

 female there is a hollow, apparently for the reception of 

 the spur.' 



When the males are provided with weapons which in the 

 females are absent, there can hardly be a doubt that these 

 serve for fighting with other males; and that they were 

 acquired through sexual selection, and were transmitted 

 to the male sex alone. It is not probable, at least in most 

 cases, that the females have been prevented from acquiring 

 such weapons on account of their being useless, superfluous, 

 or in some way injurious. On the contrary, as they are 

 often used by the males for various purposes, more espe- 

 cially as a defence against their enemies, it is a surprising 

 fact that they are so poorly developed, or quite absent, in 

 the females of so many animals. With female deer the 

 development during each recurrent season of great branch- 

 ing horns, and with female elephants the development of 

 immense tusks, would be a great waste of vital power, sup- 

 posing that they were of no use to the females. Conse- 

 quently, they would have tended to be eliminated in the 



• Mr. B. Brown, in "Proo. Zool. Soc," 1869, p. 553. See Prof. Turner, 

 in "Journal of Anat and Phys.," 1872, p. 76, on the homologieal natnre of 

 these tusks. Also Mr. J. W. Clarke on two tusks being developed in the 

 males, in "Proc. Zoolog. Soo.," 1871, p. 42. 



' Owen on the cachalot and Omithorhynehns, ibid., voL iii pp. 638, 641. 

 Otrting is qaoted fcy Dr. Zonteveen in the Dutch translat of Ibis work, voL 

 a. p 293. 



