sMtJAL SELECTION. 241' 



one-fifth more than the females.*-^ The sexes of other 

 pachydermatous animals differ very little or not at all, and, 

 as far as known, they are not polygamists. Nor have I 

 heard of any species in the orders of Cheiroptera, Edentata, 

 Insectivora and Rodents being polygamous, excepting that 

 among the Rodents, the common rat, according to some 

 rat-catchers, lives with several females. Nevertheless the 

 two sexes of some sloths (Edentata) differ in the character 

 and color of certain patches of hair on their shoulders, f 

 And many kinds of bats (Cheiroptera) present well- 

 marked sexual differences, chiefly in the males possessing 

 odoriferous glands and pouches, and by their being of 

 a lighter color. J In the great order of Rodents, as far as I 

 can learn, the sexes rarely differ, and when they do so it 

 is but slightly in the tint of the fur. 



As I hear from Sir Andrew Smith, the lion in S. Africa 

 sometimes lives with a single female, but generally with 

 more, and, in one case, was found with as many as five 

 females; so that he is polygamous. As far as I can dis- 

 cover he is the only polygamist among all the terrestrial 

 Camivora, and he alone presents well-marked sexual char- 

 acters. If, however, we turn to the mai-ine Carnivora, as 

 we shall hereafter see, the case is widely different; for many 

 species of seals offer extraordinary sexual differences, 

 and they are eminently polygamous. Thus, according to 

 Peron, the male sea -elephant of the Southern Ocean 

 always possesses several females, and the sea-lion of Forster 

 is said to be surrounded by from twenty to thirty females. 

 In the North the male sea-bear of Steller is accompanied 

 by even a greater number of females. It is an interesting 

 fact, as Dr. Gill remarks, that in the monogamous species, 

 " or those living in small communities, there is little differ- 

 ence in size between the males and females; in the social 

 species, or rather those of which the males have harems, 

 the males are vastly larger than the females. '^ 



*Dr. Campbell, in '' Proc. Zoolog. Soc.," 1869, p. 138. See also 

 an interesting paper, by Lieut. Johnstone, in " Proc. Asiatic Soc. of 

 Bengal," May, 1868. 



t Dr. Gray, in "Annals and Mag. of Nat. Hist.," 1871, p. 302. 



JSee Dr. Dobson's excellent paper in " Proc. Zoolog. Soc.," 1873, 

 p. 241. 



Tlie Blared Seals, " American Naturalist," vol. iv, Jan., 1871. 



