DERMATOGLYPHICS IN PRIMATES 109 



relationship. In addition to the separate state of these con- 

 figurational elements there are fusions manifested in two dif- 

 ferent ways : a continuous open field extending through both 

 territories, without a separation or regional differences in 

 ridge direction which would suggest two components ; a single 

 pattern centered in the interval between the sites of Th p and 

 Th d . In the prosimians the morphology of the thenar region, 

 with its single configuration, suggests a likeness to the nature 

 of the palmar thenar field. Here, as in the palm, this single 

 configuration may be interpreted as an elemental unit rather 

 than as a fusion of two fields. Actually, of course, the thenar 

 configuration in prosimians (as is true of the thenar in the 

 palm) represents Th d alone, the territory of Th p not being 

 extended proximally as a ridged area. Above the prosimians, 

 the genera having half or more of the soles presenting separate 

 Th p and Th d are: Saimiri, Aotus, Cebus, Papio, Lasiopyga, 

 Erythrocebus, Hylobates, Homo. Fusions of Th p and Th d , 

 combining both expressions mentioned above, occur in half or 

 more of the soles of: Callithrichidae in general, Alouatta, 

 Saimiri, Ateles, Lagothrix, Pithecus, Symphalangus, great 

 apes. 



Fusion into a single configurational field representing Th d 

 and I occasionally occurs. In some genera (Ateles, Cebus) the 

 fusion takes the form of a continuous open field, while the 

 probably more significant type of fusion (occurring rarely in 

 Papio, more frequently in Pithecus, and almost universally 

 in Homo) is in the form of one expanded pattern. 



The interdigital patterns I, II, III and IV, as in the palm, 

 are noteworthy for their rather consistent conformity to the 

 morphologic plan. The departures which occur are fusions 

 of adjacent configurational fields. Just as Th d and I are oc- 

 casionally blended, so sometimes are I and the central area, 

 II and III, and III and IV. Interdigital I expands into the 

 parathenar region of the central area when boundaries be- 

 tween them are lacking or shifted; this occurs frequently 

 in Hylobatidae and Pongidae. Among the prosimians, blend- 

 ing the II and III is constant in Tarsius and occurs infre- 



