“The Moderns: Chagall, Degas, Léger, Miró, Picasso and More...,” an exhibition that fills nearly all of the sprawling galleries at the Nassau County Museum of Art, in Roslyn Harbor, is really two shows in one. The first, subtitled “Selections From the Saltzman Family Collection,” displays 35 works owned by Arnold A. Saltzman, the museum’s founding president and a major benefactor, who died last year at age 97.
