Ursus have 10 physical mutations, 5 of them are Mane Mutations, 4 are Tail Mutations and the last one is the Fangs Mutation.
While it is possible to combine a Mane and a Tail Mutation, it is not possible to have two or more Mane / Tail Mutations at a time. There are two exceptions however: Bearded and Draft, which may be combined with any other Mane Mutation.
 
The Mist Mane and Tail can only be inherited from Arwii, the God of Life or from other Ursus having them. They cannot be chosen for any type of custom!

Standard Mane and Tail:

Mist Mane and Tail:

Both can only be passed down from Arwii or other beasts having these Mutations. They cannot be chosen for Semi-Customs.

Mane – Razor:

Mane – Rugged:

Mane – Bearded:

Mane – Draft:

Tail – Bobtail:

Tail – Long:

Tail – Curly:

Misc – Fangs: