Adams, R. P. (Colo. St. Univ., Ft. Collins, Colo. 80521) 1970. Contour mapping and differential systematics of geographic variation. Syst. Zool., 19: 385–390.—Algorithms are presented for automatic contour mapping of characters and displaying of the composite differential of several characters by computer. An example is given using morphological and chemical characters from Juniperus pinchotii Sudw. (Cupressaceae). Several attributes of contour mapping of geographic variation are discussed. Differential systematics is shown to be of considerable interest in delimiting areas of speciation and/or ecotypic differentiation.