Rogueclassicism may be on to something, as I have come across yet another use of cetus. This is somewhat funny to me, as I haven't been seeking them out and, as I mentioned before, I don't recall seeing the word incredibly often in the past. This use, this time a Latin genitive, is also in reference to Jonah and is found in a speech of Christ in Book 2 of Juvencus. Here are lines 697-9:
Namque propheta cavo quantum sub pectore ceti
temporis absumpsit, terrae in penetralibus altis
progenies hominis tantum demersa manebit.