Family: Arionidae
Slugs with the pneumostome in front of the mid-line of the mantle.
The British slugs which have the pneumostome situated in front of the mid-line of the mantle all belong to the family Arionidae.The internal "shell" is just a few chalky granules. All have a mucus gland just above the tip of the tail, and none has a "keel" along the back.
In Britain and Ireland, all but one of the species belong to the genus Arion. The exception is Geomaculus maculosus, which is spotted and occurs only in SW Ireland and N.Spain and Portugal.
Arion ater (L. 1758) is the well-known "large black slug", although it actually comes in a variety of colours from black, through grey to khaki, orange, brick-red to even white. Extended length 10 - 15 cm. Click on one of the images below for more details of Arion ater.
Use any one of the above images for more details of
Arion ater
There are about seven or more common Arionid slugs under 7 cm. extended length, but they are difficult for the beginner to identify from external features. Possibly the most common is Arion hortensis. Click here for more details of the smaller species.