THE TONGUE OE A SNAKE. 125 



far extended while the mouth is wide open. Snakes very 

 rarely open their mouths and use their tongues at the 

 same time. Indeed, excepting to gape, the snake does not 

 generally open its mouth ; nor invariably keep it open while 

 advancing on its prey, as illustrations often represent. 



Nature has further provided for the safety of the tongue 

 by leaving a small opening in the upper lip, or at the point 

 of the muzzle, just where no teeth are in the way, so that 

 the snake can use its tongue without exposing the sheath 

 and mouth to injury. This ' chink in the rostral shield,' 

 to use technical language, permits the free exit of the 

 tongue and the independent actions of the two muscles 

 of which it is formed, enabling the reptile to hold the two 

 fine tips close together as one tip, while passing the tongue 

 through the narrow chink, and to expand them afterwards. 



Lenz never observed any dust or small particles adher- 

 ing to the tongue ; but Mr. Arthur Nicols, the author of 

 Zoological Notes, informs me that he Jias noticed little 

 fragments of rubbish cling to the tongue and carried into 

 the mouth. Dr. Cantor also says : ' Sea snakes make no 

 use of the tongue while in the water, but considerable use 

 of it as a feeler when out of the water.' He has noticed 

 * several Indian land snakes use it to bring into the mouth 

 various small bodies, as stones, sand, twigs, which they 

 swallow to stimulate digestion.' 



This is curious and noteworthy. The power or volition 

 which can control the sheath and close the valve can, no 

 doubt, exclude these foreign particles ; as, while lapping, 

 the mouth must be moistened as well as the interior of the 

 sheath, both it and the tongue requiring frequent lubrication. 



