178 CHARLES MIDLO AND HAROLD CUMMINS 



These observations, therefore, support evidences drawn from 

 other features toward the separation of the Tarsiidae as a 

 distinct group. We can extract from the dermatoglyphics of 

 Tarsius no indications that this form stands in the line of 

 evolution of the higher primates. 



New World monkeys. Most platyrrhines contrast with Old 

 World monkeys in their characteristic arboreal life and in the 

 locomotor habits which are associated with it. One of the 

 most active brachiators, Ateles, is a member of the group. 

 From the standpoint of dermatoglyphics they are hetero- 

 geneous, in this respect also differing from the fairly con- 

 sistent traits of Old World genera. 



Callithrichidae display dermatoglyphic features which are 

 fairly uniform among the four genera observed. The family 

 is accordingly a more unified group than Cebidae, wherein the 

 diversities mentioned above are concentrated. With regard 

 to the extent of fully formed ridges, Callithrichidae retain 

 some measure of primitiveness. In the palms of Seniocebus, 

 Leontocebus and Oedipomidas, but not in Callithrix, the distal 

 portion of the central area presents a lack of definite ridge 

 formation. The proximal portion of the heel region, in at 

 least some feet of all four genera, is devoid of formed ridges 

 (as if the pelage of the corresponding region of Lemuroidea 

 had but recently disappeared and ridge formation had incom- 

 pletely progressed into the region last depilated). Retention 

 of a ridgeless region in the central area of the sole is rare, 

 being noted in only one sole (Leontocebus, fig. 47). The family 

 is fairly primitive with respect to the expressions of the basic 

 morphologic plan of patterns, but pattern intensity is lower 

 than in some Cebidae (Alouatta, Saimiri and Aotus), and 

 the difference between palm and sole is greater than in the 

 same genera. 



The six genera of Cebidae may be conveniently grouped 

 for description : (1) Saimiri, Cebus; (2) Aotus; (3) Lagothrix, 

 Alouatta; (4) Ateles. 



Saimiri and Cebus are mentioned first, inasmuch as the 

 dermatoglyphic characteristics are close to those of Calli- 



