A PASSPORT SECRETLY GREEN.

By Noel Perrin. New York: St. Martin'sPress, 1961. 181 pp. $3.50.

He is obviously a roguish elf, this author, a leprechaun with many crocks of gold. It is difficult to catch a leprechaun, but if you do and keep your eye on him, he will lead you to buried treasure.

Mr. Leprechaun Perrin's passport secretly green is a document which permits him to pass into lands of normality where persons are so predictable that his motley jigs and verbal legerdemain become irresistibly comic. He can transform the jug jug of T. S. Eliot's nightingale into sweet music as a Cambridge university don lets his eyes wonder and wander - the pot of gold becomes a pot of ale in a pub, and the riches remain the American's. Put a leprechaun on skis with rugged Americans in Switzerland and you are in for a waxy and wacky time, but the leprechaun slides all the way down to Marseilles to buy a live eel which he liberates.

Mr. Perrin can conjure up Franjoise Sagan, Monk Lewis (author of an eighteenthcentury novel filled with lubricity and sin), and a chaste angel and seat the angel and Lewis with a fierce bishop at a pious and gentle dinner. (Mademoiselle Frangoise had not yet been born, a pity.) At a wedding party Mr. Leprechaun tells one bridesmaid that he has just blown up the Kremlin, another bridesmaid that she has her dress on backwards, and a third that he has just drawn and quartered the Earl of Shrewsbury. But the heedless girls glance towards the champagne bucket, their crock of gold, and as the puckish commentator vanishes, a beautiful friendship is formed.

A drunken bum in Union Square kisses the leprechaun's hand, believing it to be clerical and blessed, a priest's. In a jiffy, the leprechaun, now a seventeenth-century Japanese dog fancier, sees his aunt smack her Pomeranian and reflects that in Japan in 1690 the old lady would have got five years in prison. On another occasion the leprechaun, now a member of a New York pigeonkicking club, is caught in ornithological flagrante delicto by a burly truck driver who wants to beat him up for cruelty to doves. The truck driver has such a muscular glance and such muscular legs that the leprechaun, lacking shrubbery, must scuttle all the way from East Fortieth Street to the Public Library.

The most dazzling treasure is the story of some Henry James papers which Mr. Perrin discovered when he was a graduate student in England, but his professor glued his eye on him and the stare stuck. With what result? The established scholar Leon Edel obtains the crock of gold and becomes an even greater treasure.

And Mr. Perrin? He becomes an assistant professor at Dartmouth, who writes charming and witty essays for English magazines like The New Statesman and American magazines like The New Yorker, and they appear collected in this book, 21 of them. The one about Henry James is the largest crock. Let your gaze wander and you will find neat red knots about the other twenty essays at the base of which are also crocks, less large perhaps, but none the less genuine in the gold of their humor. If you keep your eye on this author, you may strike it rich.