"Delacroix to Cezanne: French Watercolor Landscapes of the 19th century," at the University of Maryland Art Gallery, includes 170 little paintings. It must have been a treat to pick them. "The criterion for inclusion of a painting was simple," writes Alain de Leiris, the professor who did the choosing. "It had to be beautiful."

This lovely exhibition makes no telling points, has no central theme, and does not fit its title. It is a show given to pleasure.

It doesn't begin with Delacroix but with an 18th-century pastoral by Pierre-Francois-Leonard Fontaine (who designed the Arc de Triomphe), and it doesn't end with Cezanne, but with Paul Signac. Not all its works are landscapes (Daguerre of the daguerrotype is represented here by a moody little painting of a Gothic cloister) and not all of them are French (Richard Parkes Bonington, the Englishman, is among its stars).

Bonington is here because though he died young, in 1828 at the age of 27, he lived long enough to loosen the formal art of France. "His influence," notes the catalog, "cannot be over-emphasized." He showed his friends in France, among them Delacroix, that watercolors need not be trival works of art.

The 19th-century French unlike their English colleagues thought landscapes unimportant and watercolor prissy. "This technique," wrote Paillot de Montabert, "when fascinates so many ladies, is unworthy of the pretty hands that practice it in Paris and especially in London."

Our century admires, as did Bonington and Turner, the spontaneity of watercolor and the way the medium's liquid washes manage to convey atmospherics, light. But until the French learned from the English, they used their watercolors tightly as a sort of poor man's oils. Many early pictures here are painstakingly detailed souvenirs and studies of exotic places - Rome, Naples, the Near East.

As the 19th century progressed, and French art grew less rigid. French artists came to recognize the freedom of the medium. They could leave the studio, they could paint outside, they could finish pictures quickly. Some of them, Paul Huet, for example, or the Barbizon painter, even left the cities to immense themselves in nature. The sketchiness of the medium gave something to the spirit of Impressionism. And look at late Cezanne.

The paintings at Maryland have been borrowed from dozens of collections, 17 in Europe. There are famous artists represented - Renoir, Gauguin, Gericault, Boudin - but others who have been forgotten, Jules Jacquemart, for instance, provide some of the brightest moments in this show. It is the first large exhibition of 19th century French watercolors organized in this century.

The pictures were catalogued by Carol Hynning Smith. The exhibition, accompanied by a 270-page illustrated catalog, will travel to Louisville and Ann Arbor after closing in College Park on Dec. 4