160 CHARLES MIDLO AND HAROLD CUMMINS 



primates, introduce factors of variation in the pads concerned. 

 While it is hardly sufficient to characterize a primate as 

 essentially a walking form or a brachiator, acquaintance with 

 the precise manner of using the hand or foot is so limited 

 that distinctions cannot be drawn except in general terms. 

 Even such exacting observations on behavior as those of 

 Bingham ('32) on the gorilla, of Carpenter ('34, '35, '40) 

 on the howler, red spider monkey and gibbon, and of Nissen 

 ( '31) on chimpanzee have not disclosed a sufficient foundation 

 for detailed correlations of uses of the members and modifica- 

 tion of volar pads. It is suggestive, nonetheless, that some 

 dermatoglyphic distinctions seem to point to an association 

 between differential habits and the dermatoglyphics. The Old 

 World monkeys, the primarily walking group of primates, are 

 shown to possess high pattern intensity; the palm and sole 

 present little difference in its expression, except in genera 

 characterized by greater arboreal habit, Pygathrix especially, 

 where the palm has much higher intensity than the sole. The 

 pattern intensity is lower in New World monkeys, which are 

 distinguished from those of the Old World by their generally 

 more pronounced habits of grasping and climbing. The lower- 

 ing of pattern intensity being more marked in the sole than 

 in the palm, there is indication in this group of significant 

 differential use of the members. It is also noteworthy in this 

 connection that in the New World monkeys which display 

 areas of incomplete ridge formation the sole presents a 

 greater expense of ridged skin; in the rare instances of in- 

 complete ridge formation in Old World monkeys it is only 

 the palm which is so characterized. The great apes and man 

 provide further illustration of correlation between dermato- 

 glyphics and differential use of the members. Pongo, a 

 brachiator, shows a much higher pattern intensity in the 

 palm than in the sole ; that relationship is completely reversed 

 in man, the only primate in which the hand is virtually ex- 

 cluded as a locomotor member. In Pan, a form in which on 

 the basis of Nissen 's observations it would be difficult to 

 qualify either pair of members as dominant in locomotion, the 

 palm and sole display equal pattern intensities. 



