208 THE ZOOLOGIST. 



Of Slugs the three most destructive species are Arion ater, 

 Limax agrestis, and L. maximus. 



Avion ater (Linn.), or the Black Slug, is found in damp 

 woods, gardens, and hedges ; and during the day under stones, 

 logs of wood, and even tunnelling under ground ; it reappears, 

 however, directly after rain, and attacks all kinds of soft 

 succulent leaves. It is a great pest in gardens and fields. At 

 the same time it acts as a scavenger. This species has a variety 

 of names on account of its variable colour. Ferussac named it 

 A. empiricorum, on account of the calcareous matter found under 

 the shield having been used in medicines. It is also now 

 identified with A. jlavus, though at one time considered to be 

 a distinct species. The shell of A. ater consists of small separate 

 calcareous grains of unequal size. The colour of the body varies 

 from black to red, yellow, green, brown, and occasionally a dirty 

 yellowish white, covered with large prominent tubercles, often 

 much contracted and rounded in front and somewhat pointed 

 behind ; the mantle is paler than the rest of body ; the tentacles 

 much swollen distally ; foot with yellowish border ; slime of a 

 yellowish colour. The eggs, which are oval, white, opaque bodies, 

 take about a month to develope. The young grow slowly, and appa- 

 rently do not attain the adult condition until they are a year old. 



Limax agrestis, Linn., the Grey Field Slug, is by far 

 the most injurious to vegetation of all the land Mollusca. It 

 may be found in almost every garden and field throughout this 

 country and most parts of Europe, as well as in Siberia, 

 Madeira, and Algeria. Like all slugs, its life is dependent on 

 moisture. In dry weather we find it rolled up under a stone, 

 coming out to feed by night and during wet weather. According 

 to one authority, this mollusc feeds upon earthworms.* The 

 body is spindle-shaped, ashy grey, with reddish or yellowish 

 tinge, and sometimes mottled ; early in the year it is of a much 

 paler colour ; the shield is large ; the foot has pale sides ; and it 

 exudes an abundant viscous slime. The shell is oval and con- 

 cave on under side, very thin, marked with indistinct lines of 

 growth, with a broad membranous margin, obliquely striated. 



This species is most prolific ; as a rule seven or eight distinct 

 batches are annually produced of fifty ova each. The breeding, 

 season is from May to November. The ova are deposited in 



* In this case it has been probably mistaken for Testacella haliutidca, 

 Which preys almost exclusively on earthworms. 



