THE SERPENT'S TONGUE 143 



already been intimated, an incidental use of the 

 tongue, probably confined, or at all events most 

 advantageous to the vipers and to other venomous 

 serpents of lethargic habits. In the case of the 

 extremely active, non-venomous snake, that glides 

 away into hiding on the slightest alarm, the tongue 

 would be of little use or no value as a warning organ. 

 Between a snake of this kind and the slumberous 

 pit- viper the difference in habit is extreme. But 

 at bottom, all ground snakes are alike in disposi- 

 tion — ^all hate to be disturbed, and move only 

 when necessity drives ; and we can imagine that 

 when the tremendous weapon of a lethal tooth had 

 been acquired, when experience began to teach the 

 larger mammalians to view the serpentine form 

 with suspicion and to avoid it, the use of the 

 tongue as a warning would react on the serpent, 

 making it more and more lethargic in habit — as 

 inactive, in fact, as every snake loves to be. 



There is, I imagine, another and more important 

 use of the tongue, older than its warning use, 

 although this may date back in time to the Miocene 

 period, when the viperine form existed — a, use of 

 the tongue common to all ophidians that possess 

 the habit of exserting and vibrating that organ 

 when excited. The subject is somewhat com- 

 plicated, for we have not only to consider the 

 tongue, but the whole creature of which the tongue 

 is so small a part ; its singularity and anomalous 

 position in nature, and the many and diverse ways 

 in which the animals it preys on are affected by 



