THE TONGUE. 27 



is exquisitely constructed for its work. It is indeed 

 a wonderfal insti'iunent in the complexity of its 

 armature. The appearance and position of the organ 

 would surprise any one who searched for it for the 

 first time ; and as it is readily found, and as Peri- 

 winkles are no rarities, let me commend it to your 

 examination. The easiest mode of extracting it, 

 supposing that you are looking for it alone, is to slit 

 the thick muzzle between the two tentacles, when 

 the point of a needle will catch and draw out what 

 looks like a slender white thread, two inches or 

 more in length, one end of which is attached to 

 the throat, and the other, which is free, you will see 

 coiled in a beautiful spiral within the cavity of the 

 stomach. 



By allowing this tiny thread to stretch itself on a 

 plate of glass, which is easily done by putting a drop 

 of water on it first, which then may be drained off 

 and dried, you T\nll find that it is in reality an exces- 

 sively delicate ribbon of transparent cartilaginous 

 substance or membrane, on which are set spinous teeth 

 of glassy texture and brilliancy. They are perfectly 

 regular, and arranged in three rows, of which the 

 middle ones are three-pointed, while in each of the 

 outer rows a three-pointed tooth alternates with a 

 larger curved one somewhat boat-like in form. All the 

 teeth project from the surface of the tongue in 

 hooked cmwes, and all point in the same direction. 



The action of this sort of tongue is that of a rasp, 

 the projecting teeth abrading the surface of the plants 

 on which the animal feeds, just as the lion is said to 

 act with the horny papilla of his tongue on the flesh 



