You never forget the rival who cast a shadow over your childhood, monopolizing your father’s love and attention, clearly preferred. This is especially true if she has bitten your hand so deeply that nearly 80 years later, a scar is still there.

Hers is a face you remember, and so it is that Harry Raven, now 82, easily spots his old bête noire, Meshie  in a glass case at the American Museum of Natural History in Manhattan, even if her only identification is a sign that says “Chimpanzee troglodytes.” “There she is, that’s her,” Mr. Raven says, walking as quickly as a guy with an arthritic hip can toward a thoughtful-looking, taxidermied chimp, sitting with its legs crossed, its handlike feet large and leathery.

How does Mr. Raven know it’s her?

“How do I know you’re you?” Mr. Raven says. “I recognize the details.”

He studies Meshie, recalling a previous exhibit that included a picture of her playing with his older sister, Jane; he imitates, with a bit of an edge, Meshie’s demanding, grunting, Uuuh-wooo! uh-awooo! yelp. Mr. Raven has said that his father’s devotion to Meshie at the expense of his family caused great heartache. But standing beside the chimp, whom he has seen now and then at the museum over the years, he shows none of the emotion one might expect at the sight of an enemy vanquished.