PRODUCTION OP SOUNDS BY ANIMALS. 



513 



(fig. 255). A similar tail is possessed by some of the Opos- 

 sum tribe ; and by the Chameleon among Reptiles. 



Fig. 255. WHITE-THROATED SAJOU. 



CHAPTER XIII. 



OF THE PRODUCTION OF SOUNDS : VOICE AND SPEECH. 



675. IT is not by their movements alone, that Animals are 

 enabled to influence one another. Were it so, their commu- 

 nication would be restricted to the small amount which can 

 be effected by signs and gestures. This, however, is necessa- 

 rily the case amongst aquatic animals in general ; since they 

 are prevented by the nature of the medium they breathe 

 from producing sounds through its means. Some of them 

 appear to have the power of communicating with each 

 other by the vibrations which they can excite in the water ; 

 of this we have already noticed an example among the 

 Whale tribe ( 491) ; and there is reason to believe that certain 

 Mollusks possess a similar means of communication. 



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