GASTEROPODA. 229 



which is seen a minute black speck, now ascertained 

 to be an eye, of considerable perfection of structure. 

 The mouth is singularly formed, having only an 

 upper jaw, resembling a curved blade with a sharp 

 toothed edge, against which the soft parts of vege- 

 tables are pressed by the fleshy lips and easily di- 

 vided. The common Grey Slug of our gardens 

 (L. Agrestis) is one of the most destructive of ani- 

 mals, and is peculiarly injurious, because its ap- 

 petite is most voracious just at the season when 

 the young plants are beginning to put forth their 

 first tender leaves, and can ill sustain the merciless 

 attacks of this depredator. We know no better way 

 of eradicating this pest from a garden than by care- 

 fully searching for them individually after a shower 

 or an artificial watering, immersing them in a 

 little salt and water, which kills them instantly. 

 We have thus destroyed from one to three hundred 

 each evening for many days in succession, in a very 

 small piece of garden-ground. They may be pre- 

 vented from approaching any individual plant, by 

 strewing around it dry earth, dust, ashes, soot, &c., 

 as on such light and dry substances they cannot 

 crawl ; it must be renewed, however, of course, if 

 it happen to become wetted, the efficacy consisting 

 wholly in the dryness of the surface. 



Very different from the Slug in outward appear- 

 ance, but closely resembing it in structure and ha- 

 bits, is the genus Helix, the Snail. 



