After voice you can put the ellipsis. There's too much ands in you sentence
It emphasizes Usher's sense of terror.Repetitively saying "I dared not" shows his deep discomfort state of mind, whereas the parallel use of simple perfect tense in an interrogative sentence ("said I not") adds to the completely disoriented senses, as Usher can't tell the truth from the troublesome fiction of his own mind.