American mink
The American mink ("Neogale vison") is larger and more adaptable than the European mink ("Mustela lutreola") but, due to variations in size, an individual mink usually cannot be determined as European or American with certainty without looking at the skeleton. However, all European mink have a large white patch on their upper lip, whereas only some American mink have this marking. Therefore, any mink without the patch is certainly of the American species. Taxonomically, both American and European mink were placed in the same genus "Mustela" but the American mink has since been reclassified as belonging to its own genus, "Neovison", but has since been reclassified alongside several other weasels into the genus "Neogale".