 We apply the rule “dots only work away from the adjacent sign of disjunction, implication, or equivalence, or forward from the adjacent symbol of one of the other kinds enumerated in Group II” (where Group II includes “\((\exists x)\)”). In this case the first dot extends to the punctuation symbol \( \} \) which is allowed optionally to replace dots. No such punctuation after the quantifier (or after the negation) occur in the modern equivalent which would be:  \[ \osim (x)\phi x =_\mathit{df} (\exists x)\osim \phi x \]   or   \[ \osim \forall x\phi x =_\mathit{df} \exists x\osim \phi x \]