Cover....I'm thinking in that sentence it means: I never saw a girl of her age with so much to hide. Because before that it says "She is an underhand little thing" underhand, meaning sneaky and deceptive. So the cover is meaning she is hiding something. ----A passage from Jane Eyre They had got me by this time into the apartment indicated by Mrs. Reed, and had thrust me upon a stool: my impulse was to rise from it like a spring; their two pair of hands arrested me instantly. "If you don't sit still, you must be tied down," said Bessie. "Miss Abbot, lend me your garters; she would break mine directly." Miss Abbot turned to divest a stout leg of the necessary ligature. This preparation for bonds, and the additional ignominy it inferred, took a little of the excitement out of me. "Don't take them off," I cried; "I will not stir." In guarantee whereof, I attached myself to my seat by my hands. "Mind you don't," said Bessie; and when she had ascertained that I was really subsiding, she loosened her hold of me; then she and Miss Abbot stood with folded arms, looking darkly and doubtfully on my face, as incredulous of my sanity. "She never did so before," at last said Bessie, turning to the Abigail. "But it was always in her," was the reply. "I've told Missis often my opinion about the child, and Missis agreed with me. She's an underhand little thing: I never saw a girl of her age with so much cover."