MAMMALS 107 



the face of such facts, to attribute the evolution of these 

 structures to anything but mechanical stimulation ? 



In India and Malacca the male elephants alone are 

 provided with well-developed tusks, while the female of the 

 African elephant has tusks almost, but not quite, as large as 

 those of the male. There is no doubt that the elephant 

 lights with his tusks. In India the habits of the elephant 

 appear to resemble somewhat those of the red stag; the 

 male is often solitary, but associates in the breeding season 

 with several females, and fights with other males for their 

 possession. 



In Marsupials no well - marked unisexual characters 

 occur, but the male is usually larger and stronger than the 

 female. 



In Ornithorliynchus and Echidna there is an interesting 

 peculiarity in the male, namely, a spur on the hind-leg which 

 is hollow, and through which passes the secretion of a gland. 

 This spur fits into a groove on the leg of the female. 



