1.   Leaf crowns consisting of rows of papillae occurring as fringes round the rim of the buccal capsule or just inside the rim.

2.   Structurally they have few cuticle appendages and the buccal capsule is vestigial.

3.   In both sexes there are cervical papillae and a tiny lancet inside the buccal capsule.

4.   Microscopically they are characterised by a shallow buccal capsule with three teeth.

5.   Most are characterised by a large buccal capsule which often contains teeth or cutting plates and in some there are prominent leaf crowns surrounding the mouth opening.

6.   The well developed buccal capsule of the adult parasite is prominent as is the bursa of the male.

7.   These worms have large buccal capsules and feed by ingestion of plugs of mucosa as they move over the surface of the intestine.

8.   They are white with a markedly truncated and enlarged anterior end due to the presence of the very large buccal capsule.

9.   The external crown, if present, is compressed and so there is only a narrow opening into the buccal capsule.