248 SEXUAL SELECTION: MAMMALS. [Part II. 



tips of the horns of the great Irish elk were actually 

 eight feet apart ! While the horns are covered with 

 velvet, which lasts with the red-deer for about twelve 

 weeks, they are extremely sensitive to a blow; so that in 

 Germany the stags at this time change their habits to a 

 certain extent, and avoid dense forests, frequenting young 

 woods and low thickets. 31 These facts remind us that 

 male birds have acquired ornamental plumes at the cost 

 of retarded flight, and other ornaments at the cost of some 

 loss of power in their battles with rival males. 



With quadrupeds, when, as is often the case, the sexes 

 differ in size, the males are, I believe, always larger and 

 stronger. This holds good in a marked manner, as I am 

 informed by Mr. Gould, with the marsupials of Australia, 

 the males of which appear to continue growing until an 

 unusually late age. But the most extraordinary case is 

 that of one of the seals (Callorhinus ur sinus), a full- 

 grown female weighing less than one-sixth of a full-grown 

 male. 32 The greater strength of the male is invariably 

 displayed, as Hunter long ago remarked, 33 in those parts 

 of the body which are brought into action in fighting with 

 rival males — for instance, in the massive neck of the bull. 

 Male quadrupeds are also more courageous and pugna- 

 cious than the females. There can be little doubt that 

 these characters have been gained, partly through sexual 

 selection, owing to a long series of victories by the 

 stronger and more courageous males over the weaker, and 

 partly through the inherited effects of use. It is probable 

 that the successive variations in strength, size, and cour- 

 age, whether due to so-called spontaneous variability or 

 to the effects of use, by the accumulation of which, male 



31 'Forest Creatures,' by C. Boner, 1861, p. 60. 



32 See the very interesting paper by Mr. J. A Allen in ' Bull. Mus. 

 Comp. Zoolog. of Cambridge, United States,' vol. ii. No. 1, p. 82. The 

 iv eights were ascertained by a careful observer, Captain Bryant. 



33 'Animal Economy,' p. 45. 



