Small typo in the notes, and a question
In the notes for the lesson Dates 2 there is a small typo in the section about feminine nouns following the definite article:-
y ferch gyntaf - the fisrt girl
On to the question. And it also belongs to this particular sentence. In all the other sentences of the form "the Nth whatever" the ordinal comes before the noun. In the ones referring to "the first whatever" in the notes for this lesson it comes after. Is there any particular rule or reason?