Abstract: A study of the variations of interdigital patterns was made by collecting and analyzing a great deal of samples of random population and families from Fengxian, Shanghai etc. There are 19 types of Ⅲ , Ⅳ interdigital patterns considering the curve degree only. The interdigital pattern samples from other areas have their own major or special loop or whorl types. Many evidences show that the 19 types can be incorporated into 5 lo ts: ① one pattern in Ⅲ only , ② one pattern in Ⅳ only , ③ two patterns in Ⅳ , ④patterns in both Ⅲ andⅣ , ⑤ no patterns. There are some kinds of transitions between the types in the same lot. This new method of clustering is rather different from the old one, but has more proofs, and makes the foundation of inheritance model of this left-right asymmetric human character possible.

Key words: Interdigital patterns, Variation, Clustering