SECOND AR T SEXUA L CHARACTERS. 64? 



a means of courtship; and some species likewise perform 

 what may be called instrumental music. 



In the class of mammals, with which we are here more 

 particularly concerned, the males of almost all the species 

 use their voices during the breeding-season much more 

 than at any other time ; and some are absolutely mute 

 excepting at this season. "With other species both sexes, 

 or only the females, use their voices as a love-call. Con- 

 sidering 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 considering 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 Mycetes caraya perhaps forms an 

 exception, as does the Hylobates agilis, an ape allied to 

 man. 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 idea of the gibbon's 

 composition, excepting as regards its loudness." Afr. 

 Waterhouse then gives the notes. Prof. Owen, who is a 

 musician, confirms the foregoing statement, and remarks, 

 though erroneously, that this gibbon, "alone of brute 

 mammals, may be said to sing." It appears to be much 

 excited after its performance. Unfortunately, its habits 

 have never been closely observed in a state of nature; but 

 from the analogy of other animals, it is probable that it 

 uses its musical powers more especially during the season 

 of courtship. 



This gibbon is not the only species in the genus which 

 sings, for my son, Francis Darwin, attentively listened in 

 the Zoological Gardens to H. leuciscus while singing, a 

 cadence of three notes, in true musical intervals and with 

 a clear musical tone. It is a more surprising fact that 



* Given in W. C. L. Martin's " General Introduction to Nat. Hist, 

 of Mamm. Animals," 1841, p. 432: Owen "Anatomy of Vertebrates," 

 vol. iii, p. 600. 



