SLUGS AXD SjS'AILS. 269 



moving the broad growth of weeds and mud from the entrance 

 of pools where sheep may water, would do much good where 

 practicable. The destruction of the snails by putting gas-lime 

 or lime and strong salt over the mud when cleared out of the 

 dykes and ditches would greatly lessen the evil. 



In N. America L. humilis, and in S. America L. viator, 

 probably serve as hosts for the liver-tiuke. 



Slugs (Limacid/k) and Snails (Hblioid/k). 



Slugs and Snails are often a great pest to the gardener. jSTow 

 and then a plague of one or the other ruins our field-crops. 

 These possess a head which bears tentacles, and also a 23air of 

 eyes which may be on long stalks. The foot is flat, and the 

 rasping tongue or " radula '' is well developed. Both Snails 

 and Slugs are hermaphrodites. The eggs are laid in batches 

 in the ground and under stones. 



The slugs have only a rudimentary shell or an indefinitely 

 formed one under the mantle. Slugs mostly frequent damp 

 places, and bury themselves during the daytime in the earth. 

 The eggs are laid singly, but in groups, in the ground, and are 

 very numerous. The two chief genera are known as Arion and 

 Limax. Arion can be told by having the slime-gland in the 

 posterior extremity, and the resp)iratory orifice in front of the 

 shield-like shell. The Arions feed at night ujjon the tenderest 

 and choicest plants, but they will devour anything at times. 

 The Limaces are especially fond of indoor life, but some of 

 our worst field- pests are in this genus. All slugs excrete a 

 thick slime, and this can be exuded at least twice in rapid 

 succession, a character which we may well remember when we 

 are trying to destroy them. 



The three most destructive slugs are Limax agresiis, L. 

 maximus, and Arion ater. 



The Grey Field-slu;/ (L. ar/reatis (fig. 141) is by far the most 

 injurious land mollusc. It may be found in most gardens and 



