I have a neutered male cat who licks and carries our new kitten around. He seems very motherly to her. Why does he do this?

How old is the kitten? Is there only one kitten? Where is the mother, and how does she react? Has the male cat ever tossed the kitten around?

Some cats, male and female, just have the instinct to care for babies. As long as he's not hurting the little guy, I wouldn't worry about it. You obviously have a very special and caring tom who loves the new addition to the family.