In a food processor puree half the smoked salmon, add the cream cheese, butter, lemon juice and blend until the mixture is smooth. Transfer the puree to a bow l and stir in the dill. On the paler side of each crepe spread a thin 1/4 of th e puree mixture, top with 1/4 salmon slices. Roll the crepe tightly to enclose the filling in the crepe. Chill seam side down, covered for at least 1 hour, or until they are firm enough to slice. Slice diagonally into 1/4-inch thick spir als.