Dormice aren't mice. They are rodents, but unlike mice, they have furry tails.
Then why, I wondered, wouldn't they get a more accurate name?
Aha, Wikipedia had the answer to that: they hibernate up to six months of the year, and their name stems from the Anglo-Saxon "dormeus," meaning "sleepy." That made sense to me, although they should have been named the Anglo-Saxon for "friggin' adorable:"