Signed top left: ‘Norris’. Titled and inscribed verso: ‘Mexico XI; Offering / July 1966 / list no. 375.’ In fine condition. Inscribed in the artist’s studio notes: ‘Equal triangles and equal width bars derived from proportions of panel. First experiments on combed gesso textures in bars. Flowing green violet/red in ‘X’. Triangles: top-red oxide; r. + l., blue w/ green glaze; bottom – lt green oxide.’