When Dr. Barclay was called, I was surprised. I had expected an elderly man, but he was only in the late thirties and good-looking. Knowing Elinor, I wondered. Except for Fred, who had no looks whatever, she had had a passion for handsome men.
Beside me, I heard Mother give a ladylike snort. “so that’s it!” she said. “She had as much need for a psychiatrist as I have for a third leg.”
A beginning part of "The Lipstick" by Mary Roberts Rinehart. The short story was written in 1942, so the expression 'a third leg' might be used in a different context from these days' vulgar meaning.
The dialogue is happening in the coronor's office after Elinor took her own life.