The Study of Human Heredity. 3 N. J., and Drs. A. C. Rogers of Faribault, Minn., Wm. Healy of Chicago, Ill., Wm. T. Shanahan of Sonyea, N. Y., and David F. Weeks of Skillman, N. J. The system is a rectangular one, the symbols for the individuals ([italics]individual symbols[end italics]) of a fraternity (full brothers and sisters) being on the same horizontal line, with each later generation placed below the next earlier. Male individuals are indicated by squares, females by circles, suspended by vertical lines ([italics]individual lines[end italics]) from the horizontal line. Members of one fraternity are connected by the same horizontal line. The rank of birth in the fraternity is indicated by a serial number placed immediately above the [italics]fraternity line[end italics]. When the sex is unknown the square or circle is omitted from the end of the individual line. The fraternity line is connected by a vertical line ([italics]descent line[end italics]) to a line joining the symbols of father and mother ([italics]mating line[end italics]). The mating line may be a short horizontal one or oblique, passing from one consort to the other as emergencies of space decide. Dotted mating lines are used for illegal unions. When a marriage of one of the individuals of a fraternity who occupies a middle position in the series is to be represented, the consort is placed below and to the right or left of the circle or square and joined to it by an oblique line from which is dropped a [italics]descent line[end italics] meeting the fraternity line. In the case of illegitimate children, the descent line is dotted. For purposes of reference from description to chart each sheet of a pedigree is numbered serially with Arabic numerals. On each sheet the generations are numbered serially at the left margin with Roman numerals (I, II, III, etc) beginning with the oldest generation. In each generation each individual symbol is numbered with Arabic numerals from left to right. In the text reference is made to an individual on the chart by sheet, generation and individual number. Thus 1, II, 17 means the first sheet, II generation, 17th individual symbol from the left. For the sake of uniformity in charting the families, the paternal side of the family is placed at the left of the chart, the maternal side at the right. [italics](For display charts.[end italics] As a matter of convenience and as an aid in tracing the patient's immediate family, showing at a glance the lines of paternal and maternal descent of the defect, the descent line connecting the paternal side may be made green. Red may be used for [end]