Polydactyl cat

A polydactyl cat is a cat that has more than the usual number of toes on one or all of its paws as a result of a cat body type genetic mutation. In animals including humans, polydactyly (or polydactylism, also known as hyperdactyly) is the anatomical abnormality of having more than the usual number of digits on the hands or feet.

Normal cats have five toes on each front paw and four toes on each hind paw. Polydactyl cats may have as many as seven digits on front and/or hind paws, and various combinations of anywhere from four to seven are common, although each of the front and rear paws are typically the same. Polydactyly is most commonly found on the front paws only, with polydactyly of all four paws being less common. It is rare for a cat to have polydactyl hind paws only.

Source : http://en.wikipedia.org/wiki/Polydactyl_cat