2G6 THE PKINCIPLES OF Part II. 



same results as would follow from au actual inequality 

 in the number of the sexes ; for if each male secures 

 two or more females, many males will not be able to 

 pair ; and the latter assuredly will be the weaker or 

 less attractive individuals. Many mammals and some 

 few birds are polygamous, but with animals belonging to 

 the lower classes I have found no evidence of this habit. 

 The intellectual powers of such animals are, perhaps, 

 not sufficient to lead them to collect and guard a harem 

 of females. That some relation exists between poly- 

 gamy and the development of secondary sexual cha- 

 racters, appears nearly certain; and this supports the 

 view that a numerical preponderance of males would 

 be eminently favourable to the action of sexual selection. 

 Nevertheless many animals, especially birds, which are 

 strictly monogamous, display stroDgly- marked secondary 

 sexual characters ; whilst some few animals, which are 

 polygamous, are not thus characterised. 



We will first briefly run through the class of mam- 

 mals, and then turn to birds. The gorilla seems to be 

 a polygamist, and the male differs considerably from 

 the female ; so it is with some baboons which live in 

 herds containing twice as many adult females as males. 

 In South America the Mycetes car ay a presents well- 

 marked sexual differences in colour, beard, and vocal 

 organs, and the male generally lives with two or three 

 wives : the male of the Cebus ca/pucinus differs some- 

 what from the female, and appears to be polygamous. 5 

 Little is known on this head with respect to most other 

 monkeys, but some species are strictly monogamous. 

 The ruminants are eminently polygamous, and they 



5 On the Gorilla, Savage and Wyinan, ' Boston Journal of Nat. Hist.' 

 vol. v. 1845-47, p. 423. On Cynocephalus, Brehm, 'Illust. Thierleberi,' 

 B. i. 1864, s. 77. On Mycetes, Kengger, 'Naturgeseh. : Saugethiere 

 von Paraguay,' 1830, s. 14, 20. On Cebus, Brehin, ibid. s. 108. 



