BRITISH SLUGS 



1083 



IV. .-1. intermedins, or, as sometimes 

 designated. A. minimus, has few varieties. 

 Comjiared with .4. circitmscriptns it is 

 smaller, and less striking in colour and 

 markings, the banding being indistinct 

 and colom"ing paler. The notable charac- 

 teristic is the curious formation of the 

 skin folds, that when the animal is con- 

 tracted show as ghstening points that 

 sharply refract the hght. The outline of 

 the back shows a saw-like edge. The 

 respiratory orifice is placed rather farther 

 back than is usual with the Arionidce. 

 The colour generally a pale yellow-grey, 

 sometimes showing faint bands or with- 

 out. It is also an inhabitant of open 

 land rather than cultivated, the food 

 entirely fungi. The eggs are laid from 

 August to January, 

 hatching usually in 

 three weeks. The 

 shell-sac exists, but the 

 actual demonstration 

 of a shell is reduced to 

 a thin hning of soft 

 chalky substance. 



The shell seems to 

 be constructed by an 

 excretion from a great 

 number of lime-cells 

 that line the inner 

 membrane of the sac, 

 this organ of the ani- 

 mal ha\-ing the capacity for collecting 

 and condensing the calcareous substances 

 that become absorbed by it. 



One may even suppose that the shell 

 was, in point of fact, a consequence, rather 

 than a determinate purpose — that the 

 lime-secretion being condensed in quantity, 

 became first granular, then consolidated 

 into granules that coalesced into the shelly 

 plate of greater or less density. 



Further development necessitated this 

 plate becoming convex upward to accom- 

 modate the animal's organism. Instances 

 have occurred where the shell of the slug 

 has worn its way through the skin of the 

 animal. 



The second branch of the Arionidce tribe, 

 the Geomalacus, is represented by one 

 species in this country, namely, Geo- 

 malacus maculosus, a spotted slug. 

 The species is said to be dying out, 

 with representatives only in West Euro])e. 

 It is a hchen-feeder, and the general 



%• # 



colouring shows a curious conformity ^^'ith 

 its surroundings when resting on the rocks 

 among the C(jlour s{)lashes of these plants, 

 the back of the slug being black spotted 

 with white, and the sides yellow. The 

 power to contract exceeds that of the 

 Arion, for Geomalacus coils into a com- 

 plete ball when disturbed. The respi- 

 ratory orifice is anterior, Uke the Arion, 

 but the " shield " is considerably larger, 

 being a third of the extended length, and 

 a shelly plate further differentiates the 

 species. The shell is oval and flat, as 

 soUd as that of the Limax, and quite 

 distinct from the loose granules of the 

 Arion. The species has four varieties : 

 the type form, Geomalacus; G. fasciaia, 

 a pale greenish-grey, with stripes on the 

 back ; G. verkruzeni, 

 yellow-grey, with white 

 spots on a grey back ; 

 G. allmani. dark grey, 

 with white spots. 



SHELL FORMS OF (\) ARIOS ATER, 

 MULLER (BATH); (2) A. HOR- 

 TEXSIS, FERRUSAC. 



genus agriolimax 

 and " milax " 

 (the field slugs) 

 These slugs stand 

 apart from the true 

 Limacidce in the colora- 

 tion, in the invariable 

 absence of the longi- 

 tucUnal banding, and 

 in the distinct character of the milky 

 white slime. They are smaller in size, 

 and show a white, uncoloured ring round 

 the respiratory orifice. The body is flat- 

 tened on the sides, seen most noticeably 

 when the slug is moving, and " keeled " 

 towards the tail. 



The " shield " is a third, or more, of 

 the length of the body, rounded before 

 and behind, and marked with the line 

 concentric hues of the Limax tribe. 



The species Agriolimax agrcstis, sub- 

 variety lilacina, is a variation on the 

 pale ochre-coloured type form, being a 

 uniform pale grey tinged with a lilac 

 shade ; the body is marked with long- 

 shaped blotches of a rather darker shade, 

 the head and " tentacles " darker, 

 whilst the "keel" shows hghter. The 

 white ring that surrountls tlie resi)ira- 

 tory orifice is clearly marked. It is a 

 highly organised member of the slug 

 tribe, and shares the ]iower of adajit- 



