Nottinghamshire re-sign Australian fast bowler James Pattinson for four months of the 2019 season.
Nottinghamshire's ex-England seamer Harry Gurney retires from Championship cricket to focus solely on white-ball formats.
England captain Joe Root will face team-mate Stuart Broad when Yorkshire visit Notts in their County Championship opener.
Essex and Somerset have six players in the MCC side to face Surrey in next month's Champions County game.
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.
Follow England's summer of cricket on the BBC
BBC Sport will bring you live radio, text and in-play highlights of the 2019 Cricket World Cup and the Ashes.
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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.