Why do Americans write "Vergil" and the British write "Virgil"?

This book is something of a metaphysical head-scratcher; it is the first person narrative of the life of a woman who knows she isn't real! This appears to be a refutation of Descartes' famous "cogito ergo sum" (as if any more such were required).

It's an interesting tale with convincing characters but perhaps too much time spent dwelling on childhood (something that LeGuin has done repeatedly in my view). LeGuin claims to have been inspired directly by the Aeneid, rather than making a feminist polemic a la The Penelopiad but Lavinia laments her powerlessness in a Patriarchal society. This seems realistic rather than overtly feminist in that she doesn't have whole-sale 21st Century Western liberal attitudes; she's not agitating to abolish slavery and create a democracy, just responding in a believable manner to the situation she finds herself in - unable to choose her own husband. Lavinia rebels against her own powerlessness, however.

At the end, Lavinia is transformed into an owl; this immediately made me think of Blodauwedd from the Mabinogion, who also is the creation of another (a magician, not a poet) and unable to choose her own husband and who also rebels - and is also transformed into a owl after the fighting is over. I wonder if LeGuin had that in mind?