These present themselves as absence or defect of the digits, and as coalescence. These are very frequent malformations, and they may affect all four members, as in Fig. 17, or be limited to two or one. In cases of coalescence it is usually only the skin which unites the fingers or toes, but sometimes the muscles and tendons are united, and more rarely the bones.

Fig. 17. - Congenital deformities of fingers and toes occurring in the same person.

These defects of the fingers and toes are, like polydactylism, in a high degree inherited. This applies to the symmetrical forms, and not to such defects as may be due to mechanical interference, as by amputation.