Objects for the Microscope. 159 



Mount Torah are covered with shrubs of tamarisk broom, 

 and with clover and saintfoin ; and the herbage beneath is 

 so thronged with these snails that travellers say it is diffi- 

 cult to walk without crushing them. 



So much for the general interest of the snail ; but the 

 palate chiefly relates to its depredations, and shows us the 

 cause of its mischief-making in our gardens. 



HELIX ASPERSA. 



The mouth of the snail is armed with two horny lips, 

 sufficiently powerful to bite the tender stalks of lettuce and 

 other young vegetables ; and is further provided with this 

 palate, which is not in the mouth, but lying far back in a 

 kind of pouch which opens in front, and is capable of pro- 

 jection forward and backward, as may be well observed in 

 the water-snails kept in aquariums. We can there see the 

 opening lips and the palate thrown forward, rasping away 

 the conferva spores on the surface of the glass. The 

 palate of Helix aspersa is broad and short, set with about 

 150 rows of stout serrated teeth altogether no less than 

 21,000 in this single palate. 



UMAX, 



(Black-slug,) 



is nearly the same, but contains yet more teeth. A full- 

 sized and aged slug has 26,000 teeth, which accounts for 

 its power of destruction in our gardens. 



IIELTX HORTENSIS. 



Helix Hortends is a variety of the common garden snail, 

 reddish, yellowish, or pale gray. 



HELIX NEMORALIS. 



Helix nemoralis is the pretty banded black and yellow 

 snail, which, if long lying in the warm sun, often turns 

 rose-coloured or fine pink, to the great admiration of little 

 shell collectors. 



