150 



HARRIS HAWTHORNE WILDER. 



figure which has no morphological significance, in the direction of 

 A, or B, or C. The whorl, in formula writing, may be designated 

 as W, and the three derived types just given, may be distinguished 

 by the triradius that is wanting, as A, B, or C, respectively. 

 Aside from these, there are compound types, where two of the 

 triradii fail, and where the ridges flow out in two directions. Of 



W 



B 



C AC 



FlG. 9. Diagram showing the types of hallucal pattern. W is a whorl, with 

 the three triradii all present, A, B, and C. In type A triradius A, the distal one. 

 is lost, and the ridges flow out between the first and second digits. In type B the 

 triradius of the name, the tibial one, is lost while A and C remain, and in type C, 

 the fibular triradius (C) is lost, or nearly so, giving an outlet for the ridges in that 

 direction. Types AC and BC may be interpreted as compound types, explicable 

 from the others, especially C, where the two triradii A and C lie near together. In 

 AC the remaining triradius is assumed to be B, and in BC it is A. In AC the rem- 

 nant of the pattern lies to the left of the triradius; in BC below it. 



