At the end of the last century, Mr. Bruce Lowe, assisted by Mr William Allison, listed some 50 tap-root mare in numerical order. The order was based on the number of direct descendents of each mare, through the female line, who had won the Derby, Oaks and St. Leger up to that time; the number 1 being allocated to the family whose foundation mare could claim the most winners of these three classic races among her descendents in tail female at the time the system was compiled by Bruce Lowe; the number 2 to the family with the second largest number of these classic winners among its offspring; and so on down the scale. According to this figure system, each female line was given a family number by which it is now usually known. The principal tap-root mares, with their Bruce Lowe family numbers, and some of their more famous descendents through direct female line are provided here.