RUSSMANNS from Hannover

I am trying to trace the emigration of my GGrandfather, Arjen RUSSMANN, born Hannover, 1858. According to an 1890 Chicago Voter's List, he emigrated between 1868 and 1870 and settled in Illinois.

I cannot find him on any Ship's Passenger Lists..believe his father's name was Herman. Arjen would have been between 10 and 12 when he emigrated. Any help greatly appreciated. I have tried to translate this message into into German.