PALM AND SOLE STUDIES. 



399 



types that arise from the loss of each of the triradii, one at a time, 

 and also the three arising from the simultaneous loss of any two, 

 we have seven primary types, in which the variations are due to 

 differences in the originally embracing folds, with their triradii, 



FIG. 10 FIG. ii 



FIG. 10. A typical whorl pattern, composed of concentric circles. By cutting 

 this through the center, as along the line, and then sliding the two halves as in Fig. 

 ii, an S-shaped spiral is produced. 



FIG. ii. An S-shaped spiral the result of sliding the two halves of Fig. 10, 

 as explained in the text. This form is frequent in all kinds of patterns. 



FIG. 12 FIG. 13. 



FIG. 12. An S-shaped pattern surrounded by its denning triradii. 



FIG. 13. An S-shaped pattern, showing the axis along which 



the slipping may have taken place. 



