*adds one more reply to Nadia's note*
One more thing dear. The term Metamorphmagi refers to a group or collective of witches and wizards who can metamorph or when talking about the subject in general. Metamorphmagus is a single witch or wizard who can metamorph. Animagi is the collective or group term for transifguring into an animal or when talking about the subject in general. Animagus is a single persona who can transifgure themselves into an animal.

(Also i must apoligize i was spelling Metamorphmagus and Metamorphmagi without the 'm' in magus on the end. I had apparently copied it down wrong. Sorry you got stuck with such an absent minded Professor LOL I believe that was the confusion She-Who-Must had with my explainations.)