Negotiations between Bank of America Corp. and the Justice Department have hit a snag over whether the firm should pay a cash penalty for the dealings of Countrywide Financial Corp. and Merrill Lynch & Co., the Wall Street Journal reported today. Bank of America has offered $13 billion to end the government's mortgage-securities probe, including a combination of fines and consumer assistance, which could include credit for measures such as writing down the values of mortgages for struggling homeowners. But the Justice Department is demanding billions more — and wants a bigger chunk in fines. Bank of America, which has already shelled out some $60 billion for crisis-era legal problems, has told the Justice Department it is willing to pay for the past misdeeds of Countrywide and Merrill Lynch — but not at levels it considers overly punitive.