Commencing two years from the effective date of the revision of this chapter in the year 1977, in all cases in which the parties are entitled to a trial by jury and in which a jury trial is properly demanded, the action shall be tried to a jury composed by six members unless the parties agree, with the consent of the court, upon a lesser number provided, however, that in criminal actions involving alleged felonies, the accused shall be entitled to a jury composed of twelve members.