Describe the appearance of Roderick Usher's deceased sister

From the text:

A striking similitude between the brother and sister now first arrested my attention... The disease which had thus entombed the lady in the maturity of youth, had left, as usual in all maladies of a strictly cataleptical character, the mockery of a faint blush upon the bosom and the face, and that suspiciously lingering smile upon the lip which is so terrible in death.