Meursault and Barretter;
Ordinarily I would not wade in to such a heated debate, but I sensed (correctly or otherwise) that you both might appreciate my understanding of the -is or -es debate - which, incidentally, has been the subject of many theses.
I believe the answer is quite simple here; we must remember that the original quote was written prior to the late Augustan period when the written language was documented far more formally, and therefore at the time Virgil was writing there existed less clearly defined rules.
(As an additional comment here, the same was the case with Chaucer and Shakespeare - they did not misspell, or use bad grammar, but rather lived in times when society was far less pedantic about the fluidity of our great language.)
However, if you wish to get serious about the analysis of this quote, I would suggest you research Virgil's use of the third declension accusative plural endings (-is) as this is something he does commonly.
My own belief is that he did so because it sounds better when read; -is has a long vowel sound, -es has a short, rather staccato sound. I simply think he was being poetic; and I'll stick my neck out and say he's probably earned the right to do so.
Before I make my final comment, I would like to acknowledge that I am a relative newcomer to this forum, and unlike the two of you am a net consumer of the information herein, whereas you both seem to be net suppliers.
However, the tone of your discussion was distinctly uncomfortable for me, and I suspect others, in what is ordinarily a very pleasant and friendly (virtual) place to be.
'nough said?