Oregon Department of Agriculture guides
Slug or Snail?
no visible shell or a small shell that cannot contain their body.
Continue to slugs
a coiled shell that can contain most or all of their body.
Continue to snails
Parts of a slug
Common slug identification key
With visible shell
Without visible shell
1. Pneumostome in anterior half of mantle
2. Pneumostome in middle or posterior half of mantle.