332 SEXUAL selection: man. PartIL 



more particularly concerned, the males of almost all the 

 specres use their voices during the breeding-season 

 much more than at any other time ; and some are abso- 

 lutely mute excepting at this season. Both sexes of other 

 species, or the females alone, use their voices as a love- 

 call. Considering these facts, and that the vocal organs 

 of some quadrupeds are much more largely developed 

 in the male than in the female, either permanently or 

 temporarily during the breeding season ; and consider- 

 ing that in most of the lower classes the sounds produced 

 by the males, serve not only to call but to excite or allure 

 the female, it is a surprising fact that we have not as yet 

 any good evidence that these organs are used by male 

 mammals to charm the females. The American Mijcetes 

 caraya perhaps forms an exception, as does more pro- 

 bably one of those apes which come nearer to man, 

 namely, the Kijlobates agilis. This gibbon has an 

 extremely loud but musical voice. Mr. Waterhouse 

 states,^^ ''It appeared to me that in ascending and 

 '^ descending the scale, the intervals were always exactly 

 " half-tones ; and I am sure that the highest note was 

 " the exact octave to the lowest. The quality of the 

 " notes is very musical ; and I do not doubt that a good 

 " violinist would be able to give a correct id'ea of the 

 " gibbon's composition, excepting as regards its loiid- 

 '' ness." Mr. Waterhouse then gives the notes. Pro- 

 fessor Owen, who is likewise a musician, confirms the 

 foregoing statement, and remarks that this gibbon 

 " alone of brute mammals may be said to sing." It 

 appears to be much excited after its performance. Un- 

 fortunately its habits have never been closely observed 

 in a state of nature ; but from the analogy of almost 



28 Given in W. C. L. Martin's 'General Introduct. to Nat. Hist, of 

 Mamm. Animals/ 1841, p. 432 ; Owen, ' Anatomy of Vertebrates,' vol. 

 iii. p. 600. 



