Arms of Rowland Liston of Knebworth

Rowland Liston
From The Blazon of Gentrie by Sir John Ferne (1586) p245

Blazon: Ermines on a chief azure, three crowns or


Variations on Ermine

Variations on the ermine fur

“Furs” are various patterns in heraldry created to mimic the appearance of actual animal furs. First is ermine, then ermines (ermine in negative, as it were), followed by erminois (in which the sable spots of the ermine are placed on a field or) and pean (or spots on a sable field). 

Ermine is the most frequently used fur in heraldry, and can be seen both on the field and on charges. Ermine spots (which have various designs) can also be used as charges in their own right, although this was rare.