268 SEXUAL SELECTION : MAMMALS. [Part IL 



From the reasons given wlien discussing the voice of the 

 stag, we may reject the idea that the odor serves to bring 

 tlic females from a distance to the males. Active and long- 

 continued use cannot here have come into play, as in the 

 case of the vocal organs. The odor emitted must he of 

 considerable importance to the male, inasmuch as large 

 and complex glands, furnished with muscles for everting 

 the sac; and for closing or opening the orifice, have in 

 some cases been developed. The development of these 

 organs is intelligible tlirough sexual selection, if the more 

 odoriferous males are the most successful in winning the 

 females, and in leaving oftspring to inherit their gradually- 

 perfected glands and odors. 



Development of the Hair. — We have seen that male 

 quadrupeds often have the hair on their necks and shoul- 

 ders much more developed than in the females ; and many 

 additional instances could be given. This sometimes 

 serves as a defence to the male during his battles; but 

 whether the hair in most cases has been specially devel- 

 oped for this purpose is very doubtful. We may feel 

 almost certain that this is not the case, when a thin and 

 narrow crest runs along the whole length of the back ; for 

 a crest of this kind Avould afford scarcely any i)rotection, 

 and the ridge of the back is not a likely place to be in- 

 jured ; nevertheless such crests are sometimes confined to 

 the males, or are much more developed in them than in 

 the females. Two antelopes, the Traf/elaphus scn'ptxs " 

 (see Fig. 68, p. 285) and Portnx picta, may be given as 

 instances. The crests of certain stags and of the male 

 wild-goat stand erect, when these animals are enraged or 

 terrified ; '* but it can hardly be supposed that they have 



'^ Dr. Gray, ' (ilcaninps from the >ronagerie at Knowslcy,' pi. 28. 



'^ .Iudn;e Caton on the wapiti, ' Transact. OUawa Acad. Nat. Sciences,' 

 ISr.S, pp. 36, 40; Hlvth, 'Land and Water,' on Capra (egagrm, 1867, 

 p. 37. 



