A 41-year-old Hamilton Parish man was last night in critical condition, after his motorcycle struck a bus in morning traffic on Middle Road, Southampton.The rider was being treated for head injuries in King Edward VII Memorial intensive care unit. No other injuries were reported. The accident, at 7.15am near Five Star Island, saw traffic diverted for two hours while police investigators examined the scene.Witnesses to the crash are asked to contact Pc Bianca Glasford of the Roads Policing Unit, at 295-0011.