Was James Joyce confused about "prone" and "supine" or am I?

I've been re-reading "Ulysses" and noticed this

Stephen totters, collapses, falls, stunned. He lies prone, his face to the sky

(emphasis mine) and

Stephen, prone, breathes to the stars.

and a little later, Bloom

bends again and undoes the buttons of Stephen's waistcoat

Full text of the novel (massively NSFW in case you don't know): http://www.gutenberg.org/files/4300/4300-h/4300-h.htm

So, according to everything I know, "prone" should mean he was lying face down, but these passages imply he's lying face up.

Solution 1:

This dictionary http://www.oxforddictionaries.com/definition/english/prone says that prone means

"Lying flat, **especially** face downwards:" 

(my emphasis) - the emphasis implies that it's "not necessarily" face down.

This one http://dictionary.cambridge.org/dictionary/english/prone says

prone: adjective (LYING DOWN)
› formal: lying face down:

which suggests that the simple "lying down (not necessarily face down)" is an informal meaning.

This one http://www.merriam-webster.com/dictionary/prone lists two seperate meanings:

a :  having the front or ventral surface downward
b :  lying flat or prostrate

So, that's three different dictionaries suggesting that it's acceptable to use "prone" to simply mean "lying on the ground", not necessarily face down.

I think that Joyce is off the hook on this one.

Solution 2:

If you cast Steven Dedalus in The Exorcist, he might lie prone, looking at the stars.

Prone is derived from the Latin pronus: bent forward, leaning forward, bent over. It has meant lying face-down since the 1570s.

However, when it comes to Joyce, I would not care to argue.