CrenuB 

 Arion. 



136 INTRODUCTION TO ZOOLOGY chap. 



Some Common Genera of Slugs. 



The genus Arion includes the common black 

 slugs living in woods and gardens. The respiratory 

 aperture is in the front half of the mantle-shield ; 

 the shell is represented by a few calcareous grains under the 

 back part of the shield ; a slime gland is present in the tail. 



Arion ater if full grown may be 4 inches long when ex- 

 tended, but the body may be contracted into a lump (Fig. 87). 

 The tentacles are swollen at the tip, and black; the colour 

 of the body varies, it may be black, brown, red, yellow, or 

 green ; the shield is lighter than the rest of the body ; the 

 foot usually has a yellow border. 



Arion hortensis is only | an inch long ; it is common in 

 gardens. The shell gi-anules are compact, forming an oval 

 mass ; the body is marked with grey lines or stripes. 



Limax is the genus which includes the large grey 



Limax slugs. The shell is like a curved plate; it is 



covered by the hind part of the mantle-shield, 



which has usually concentric lines on it. The respiratory 



opening is in the back half of the mantle-shield. The foot 



has no slime gland. 



Limax marginatus ( = Sowerhyi) is the Tree Slug ; the colour 

 of its body is yellow or reddish-brown with black speckles, 

 its slime is colourless, and its shell resembles shagreen. 



Limax flamis (the Cellar Slug) is 4 inches long and yellow 

 with white and black specks ; it has yellow slime and a con- 

 centrically marked shield. 



Limax agrestis (the Grey Field Slug) is usually about f of 

 an inch long and has a concentrically marked shield, an ash- 

 grey body, and milky slime. It is a very common and 

 destructive species, specially characteristic of damp spots. 



Liniax maximus may be as much as 6 inches long ; its body 

 is grey with black spots, tentacles long and purple, and shield 

 regularly striate ; the shell is oblong and | an inch long. 



This genus is peculiar amongst slugs in being 



or the ' carnivorous ; it preys on worms and on smaller 



"Snail slugs and snails. It is also characterised by pos- 



Slig- sessing a distinct ear-shaped shell, with a small 

 terminal spire of half a whorl. 



This shell and the mantle-shield below it are placed quite 



