As they gaze on Madeline, the narrator commented on her resemblance to Roderick. What does he tell the narrator?

He actually doesn't comment on their similarities..... Usher read his mind.

Having deposited our mournful burden upon tressels within this region of horror, we partially turned aside the yet unscrewed lid of the coffin, and looked upon the face of the tenant. The exact similitude between the brother and sister even here again startled and confounded me. Usher, divining, perhaps, my thoughts, murmured out some few words from which I learned that the deceased and himself had been twins, and that sympathies of a scarcely intelligible nature had always existed between them.