DERMATOGLYPHICS IN PRIMATES 179 



thrichidae. The advance of ridge formation, especially in 

 Cebus, is greater than in Callithrichidae, and the frequency 

 of individuals presenting incomplete ridge formation is les- 

 sened. In Saimiri and Cebus, especially the former, pattern 

 intensity is higher than in Callithrichidae. The excess of 

 pattern intensity in the palm is less in Saimiri than in Cebus 

 or the Callithrichidae, and in this respect, as well as in the 

 higher total intensities, Saimiri is more primitive than the 

 Callithrichidae or Cebus. 



The greatest primitiveness to be found in New World 

 monkeys is observed in Aotus : a large expanse of unridged 

 skin; a high pattern intensity; slight difference in pattern 

 intensity between palm and sole; a nearly perfect adherence 

 to the basic morphologic plan of pads and patterns (so nearly 

 perfect, in fact, that this genus has served constantly as a 

 reference standard). 



When compared with the New World monkeys previously 

 mentioned, Lagothrix and Alquatta represent a greater ad- 

 vance with reference to complete ridge formation. As signs 

 of primitiveness, however, both genera show high pattern 

 intensities, and they present frequent indications of central 

 patterns. Alouatta displays a smaller difference between palm 

 and sole in pattern intensity, in this being less specialized than 

 Lagothrix. Both genera have prehensile tails which bear 

 dermatoglyphics, a trait which they share with Ateles. 



Ateles is the most highly specialized representative of the 

 New World monkeys, and it seems quite probable that its 

 dermatoglypiiic specialization may be correlated with the 

 brachiating habit. Morphologically the palm is distinctive; 

 it is elongated and there is a broad V-shaped configuration 

 including and surrounding the parathenar area. (This V-- 

 shaped configuration, as well as the occurrence of palmar 

 patterns, is conspicuously different from the appearance of 

 the dermatoglyphics in another pronounced brachiator having 

 a similarly elongated palm, Hylobates.) The extreme reduc- 

 tion in pattern intensity of the third interdigital area of the 

 palm is a unique exception to the trend among all monkeys, 



