Morphological and genetic study of seam figures in the hallucal area

The seam figure was defined in this paper as a number of ridges ending on the same line in right-angled relation to a part of the system. This characteristic occurs in various types of hallucal patterns and most frequently in whorls. In Japanese material, the frequency of the seam figure on the left sole (16.7%) is significantly higher than on the right sole (8.2%), but no sex difference was found. It is revealed from twin material that the presence of this trait is genetically controlled. Similar phenomena in areas other than the hallucal and in the 'ridges-off-the-end' syndrome were discussed.