Plural of iris
Ann, you are correct in your statement that the word octypus comes from
the Greek and that the Greek plural is octypodes. I would suggest,
however, that this plural is very rarely used, even in Australia.
Octypuses has been accepted in English since 1758 and appears, according
to the OED, to be derived from the latin use of the Greek word. During
my Californian period, I was a marine biologist and taught marine
biology and oceanography in the US. I do not remember hearing octypodes
used there or even at Oxford where Greek, ancient rather than modern,
was common knowledge amongst the students.
Again, the OED states that the plural of iris are both irides and irises
with approximately the same etymology, however, it also states that the
use of irides is usually restricted to the eye.
Ian, in Ottawa where I. cristata opened today.