332 
SEXUAL selection: man. 
Part IL 
lately 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 Mycete^ 
caraya perhaps forms an exception, as does more pro- 
bably one of those apes which come nearer to man, 
namely, the Hylobates agilis. This gibbon has an 
extremely loud but musical voice. Mr. AVaterhouse 
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 idea of the 
gibbon’s composition, excepting as regards its loud- 
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 
all other animals, it is highly probable that it utters its 
musical notes especially during the season of courtship. 
Given in W. C. L. Martin’s ‘General Introduct. to Nat. Hist, of 
Mamm. Animals/ 1S41, p. 432; Owen, ‘Anatomy of Vertebrates,’ voL 
iii. p. 600. 
