why a lion and emus?

I wrote to [his American publishers] expressing (with moderation) my dislike of the cover for The Hobbit. It was a short hasty note by hand, without a copy, but it was to this effect: I think the cover ugly; but I recognize that a main object of a paperback cover is to attract purchasers, and I suppose that you are better judges of what is attractive in USA than I am. I therefore will not enter into a debate about taste -- (meaning though I did not say so: horrible colours and foul lettering) -- but I must ask this about the vignette: what has it got to do with the story? Where is this place? Why a lion and emus? And what is the thing in the foreground with pink bulbs? I do not understand how anybody who had read the tale (I hope you are one) could think such a picture would please the author. ...

the rest here