Board Thread:The Reference Desk/@comment-24894325-20160309221053/@comment-5918438-20160802023946

I'd say if we can't find a source for "vitrious" as a spelling, we should assume that it was written that way on regeneration in error, and the actual, existing word, "vitreous", was meant in the script. "Vitrious" just seems to be a local spelling mistake.