180 CHARLES MIDLO AND HAROLD CUMMINS 



though it is matched or closely approached in other brachiators 

 - Hylobates, Pongo and Pan. A similar situation obtains, 

 curiously enough, in the soles of the same genera, also in 

 Symphalangus and in Callithrix (notwithstanding that Calli- 

 thrix is a non-brachiating primate and that the sole would 

 not be concerned in brachiating suspension). 



In examining the eight genera of New World monkeys for 

 the difference between pattern intensities of palm and sole, 

 the comparison may be made conveniently with the use of a 

 palm/sole index of pattern intensity, supplementing the 

 graphic record shown in figure 597. An index of 100 indicating 

 equality, Aotus, Alouatta and Saimiri (with respective indices 

 of 112, 113, and 118) present relatively small excesses of 

 pattern intensity in the palm. Callithrix, Oedipomidas and 

 Lagothrix (with indices 137, 147, and 150) show considerably 

 greater membral difference, while Cebus (168) and Ateles 

 (191) show still greater difference. It has been stated previ- 

 ously that the Old World monkeys present little difference 

 in pattern intensity between palm and sole, and at this point 

 the actual indices may be listed for ready comparison with the 

 New World monkeys : Cercocebus, 92 ; Lasiopyga, 106 ; Papio, 

 108; Pithecus, 114; Erythrocebus, 114; Pygathrix, 136. This 

 exceptional position of Pygathrix, with regard to large dif- 

 ference between palm and sole, is not alone in rendering this 

 genus a distinctive member of its group; there are other 

 outstanding departures, as noted previously and below. 



The palm and sole of New World monkeys show small dif- 

 ferences between the corresponding thenar and hypothenar 

 groups of configurational areas, and the greatest difference 

 observed in comparing the two groups in the same member 

 is found in Ateles. Crossed comparisons of the thenar group 

 in the palm and hypothenar group in the sole show wider differ- 

 ences in Oedipomidas, Ateles, Lagothrix and Cebus than in 

 other genera, Ateles being the most distinctive in this respect. 

 With regard to the distal, intermediate and proximal groups 

 of configurational areas (fig. 601), the platyrrhines show two 

 different trends of interrelationships in the palm and sole. 



