Jacketed in Anglican purple, the new book by Louis Auchincloss, his 34th, comprises a dozen short stories and a dozen page-long "sketches." The short stories, with settings that range from Florence in the 1920s to New York in the 1970s, are populated with the usual Auchincloss cast--rich dowagers, Episcopalian priests, nannies, artists patronized by the bored and wealthy, foreign service officers, and, of course, lots of lawyers. The sketches, mostly brief portraits of contemporary New York, serve little purpose other than to pad the book beyond 200 pages. Auchincloss, who is also a practicing lawyer, a historian, and a literary critic (Edith Wharton, Henry James), writes in the same elegant, bloodless style as in the best of his novels--and irony is still the engine that drives the tales, that keeps us reading.

Many of the stories, including the eponymous "Narcissa" (about a rich dowager who poses nude for a foppish artist), are concerned with vanity. I found these tales pleasant but flat. And calling them "fables" is inaccurate; there's no didactic point being made in them.

The best Auchincloss fiction is set in law offices and the corridors of corporate power, and so it is here. The author moves his characters into positions in which they have to make excruciating ethical decisions, frequently choices between betraying a friend and being faithful to a professional code. These stories truly are fables.

But there's a problem in the new book. In several of the "moral-choice" stories, there's a disturbing lack of sincerity. Irony takes the upper hand, and we're not really sure Auchincloss is taking the whole matter very seriously.

An example is "The Tender Offer." An aging lawyer, about to retire, is devoted to collecting New York iconography and studying the city's history, a good patrician pursuit. After his major client, an old-line bank, is "merged, taken over, consumed, raped, by First National Merchants' Loan," he's put on a case for which he has little taste. He's representing a conglomerate with the evil-sounding name Zolex, which is secretly preparing a tender offer to devour gentle Pilgrim Publishing. The lawyer also happens to be a friend of the head of Pilgrim. Over lunch, between cocktails and appetizers, the lawyer has to decide whether to violate his oath in order to do "his duty as a friend. And as a citizen. And as a student of New York history." He makes his decision bravely--only to have it backfire viciously on him.

The problem is that Auchincloss treats the story with such a light touch that we're not sure whether he's kidding or not. To violate one's oath for a friend sounds plausible. But for the sake of the study of New York history! And what are we to make of this description of the lawyer's moment of decision?

"His heart was beating rapidly, and the big crowded room blurred before his eyes. Through his mind throbbed the slow, marching melody of the old hymn: 'Once to-o ev-er-y man a-a-and na-a-tion, comes the-e-e mo-o-ment to-o decide.' "

We're never exactly sure where Auchincloss' sympathies lie in any of his books--his tone of neutrality, of benign indifference is one of the things that makes him such a good writer. But in many of the stories in "Narcissa," I'm baffled by what seems to be an ugly sort of un-Auchinclossian cynicism.

Another example comes in "The Seagull." Here, a priest decides to become an adulterer in a good cause. He sleeps with a woman parishioner to help save her self-respect and sanity. It would make a good tale if we could believe that the minister really was acting from Christian charity. But the minister, the narrator of the tale, protests too much: "You will ask if I derived pleasure from the act. Certainly I did. Had I not, I could never have convinced her that she was lovable. I derived and conveyed intense pleasure. But I believed that I was performing a kind of sacrament."

Calling adultery a sacrament is going a little too far. Again, by the way, the hero's ethical choice proves disastrous, to the point of hyperbole.

But not all the stories suffer from insincerity. "The Fabbri Tape"--the best of the 12 and the only one that, fleshed out, would make an excellent novel--also concerns an ethical choice, a distinguished lawyer deciding to help a distinguished judge fix a case and then covering up for him. "I was strangely clear in my mind and heart," says the lawyer, Mario Fabbri, "that I was not only justified but praiseworthy in my act of judicial subordination." His point is that, by covering up, he gave people confidence in the social and judicial order; by revealing all, he would destroy their respect for America. And he adds: "Supposing--just supposing--it had been possible to cover up the Watergate break-in and spare the world a knowledge that has disillusioned millions with the very concept of democratic government. Would you not have done so?"

The moral calculus in "The Fabbri Tape" is both more outrageous and more convincing than in "The Tender Offer" and "The Seagull." We're back to the brilliant benign indifference that Auchincloss shows in his best novels--"The Embezzler," "A World of Profit," "Venus in Sparta," "The House of the Prophet" and "I Come as a Thief" (to list them in something like an order of preference).

Auchincloss is still one of our best writers of fiction--and perhaps the only novelist to deal seriously with what most of us spend a third of our time doing, namely working. "The Fabbri Tape" and a few less ambitious stories--"The Cup of Coffee" (about office politics), "Charade" (about a proposed marriage of convenience between a rich homosexual and a poor but well-bred schoolteacher) and "Marley's Chain" (about a man troubled by the abundance fate has given him)--confirm that judgment. I only hope his 35th book is a novel in which his penchant for irony doesn't obscure his talents as a moralist and as a fine observer of the leisure class when it's not at leisure.