As far as I know, the surname Morris means swarthy, or dark skinned, it is the same derivation as the first name Maurice which comes from the latin Maurus which also meant dark skinned.

There is much debate on the origins of the term "Morris Dancing" - but many people believe it comes from Moorish Dancing - The Moors were originally the inhabitants of Mauretania (North-West Africa). Given that the earliest references to Morris Dancing in England is in the 1400s or 1500s, I'm not sure if there is a connection, but if there is - it is quite a small one!

Cheers

Squeezy