Thanks for the article. Screwed up Latin plurals really grate on me, especially the ignorant-and-proud-of-it perverse overgeneralization of the
-ii plural. I've seen quite a lot of
penii for instance, and once I came across
Apiciusii (which was particularly frustrating, because for that word the correct plural,
Apicii does actually end in
-ii, so they had to go the extra mile to get it wrong.)
One note though:
While "octopus" should really be third declension, treating it as second declension seems to be very old. Compare the similar and often synonymous
polypus, which is treated as second declension in Latin (plural
polypi) even though historically it should be third (plural *
polypodes). Furthermore, it turns out that
even in Greek it was sometimes treated as second declension. I mean, if it only happened in latin we could attribute it to dumb Romans making up "pseudo-Greek plurals," but if even the Greeks got it wrong then... well I guess it isn't wrong
Note also the better known inconsistant treatment of
Oedipus (again, both in Latin and
Greek). Of course we don't get much call to pluralize Oedipus in English.