THE BLACK PRINCE
by IRIS MURDOCH 366 pages. Viking. $7.95.
At mid-whirl in Iris Murdoch's latest witch dance, one of her characters stammers: "I didn't know ordinary educated middle-class English people could behave the way we behaved."
This cry from the well-mannered heart carries across 15 novels and almost 20 yearsin fact from Under the Net, which the author wrote in 1954.
With a perversity hardly matched since Shakespeare put an ass's head on Bottom, Miss Murdoch has made a career out of bewitching into beastliness the discreetly charming British bourgeoisie. In her neo-Gothic tales, subtle spells fill the air until respectable Londoners seem to...