PRODUCTION OF SOUNDS BY ANIMALS. 513 
(fig. 255). A similar tail is possessed by some of the Opos- 
sum tribe ; and by the Chameleon among Reptiles. 
a Pig. 255.—WHITE-THROATED Sasov. 
> 
t CHAPTER XIIL 
: OF THE PRODUCTION OF SOUNDS: VOICE AND SPEECH. 
h 
675. Ir is not by their movements alone, that Animals are 
enabled to influence one another. Were it so, their commu- 
hication would be restricted to the small amount which can 
effected by signs and gestures. This, however, is necessa- 
ily the case amongst aquatic animals in general ; since they 
prevented by the nature of the medium they breathe 
rom producing sounds through its means. Some of them 
Appear to have the power of communicating with each 
er by the vibrations which they can excite in the water; 
this we have already noticed an example among the 
e tribe (§ 491); and there is reason to believe that certain 
ollusks possess a similar means of communication. 
; LL 
