Nottinghamshire's left-arm paceman Harry Gurney is to play for Melbourne Renegades in the Big Bash.
The County Championship will see three teams promoted and one relegated next year to create a 10-team top tier from 2020.
Nottinghamshire wicketkeeper Tom Moores has been rewarded for his fine 2018 season by being handed a new three-year contract.
Relegated Worcestershire sign batsman Riki Wessels from Nottinghamshire on a three-year deal.
Audio & Video
BBC Sport relives Sir Garfield Sobers' six sixes in an over for Nottinghamshire against Glamorgan in Swansea, 50 years on.
Glamorgan bowler Malcolm Nash says "five minutes of his life" when he was struck for six sixes by Sir Garfield Sobers is still spoken about 50 years on.
Analysis and opinion from the BBC's cricket correspondent.
How to follow cricket on the BBC
BBC Sport brings you live radio commentary from England's Test series against India.
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How to get into cricket
How to get into cricket - physical exertion with a chess-like element in matches which range from half an hour to five days.