Where'd the name "Irys" come from?

[Rodan, Messenger of the Skies]

Isn't the official name Iris? Was this a fan name given because the name "Iris" might invoke images of the iris of an eye? What's the deal?

[Mothraleo]

<font color='#0000FF'>Just a different spelling like Angilas, or Anguirus.

[Rodan, Messenger of the Skies]

Of course it's a different spelling. But where'd it come from? Is it the official Daiei Japanese name? A fan name? What?

[kpa]

It's just an alternate spelling from Japan. 'Iris' appears on most Daiei publicity material, but 'Irys' was used occassionally-- including in a book by Shinji Higuchi.