DERMATOGLYPHICS IN PRIMATES 103 



It is evident that central pads reach their highest develop- 

 ment in certain platyrrhines. This degree of development is 

 not shared by all members of the group, which embraces 

 variations from the diagrammatically complete expression of 

 Aotus to the absence of central pads in Ateles. The prosimians 

 are more erratic. Central pads are absent in Tarsius and 

 Perodicticus, and only incompletely and imperfectly expressed 

 in the other available genera. The absence of definable central 

 pads in adult catarrhines and in some genera of the lower 

 groups may be the result of ontogenetic regression. The 

 published photographs of fetuses of a catarrhine monkey, 

 Pithecus (Schultz, '37 b), and man (Cummins, '29) suggest 

 the occurrence of ill-defined central pads in the hand ; though 

 completely suppressed in later development, their presence 

 in the fetus of forms which as adults lack these pads is of 

 interest. Their history is like that of the border pads in man, 

 which subside and undergo more or less complete absorption 

 into the general surface. 



Comparisons between palm and sole, Interdigital pads II, 

 III and IV tend to be more lowered in soles than in palms, 

 though in those forms which present the most extreme lower- 

 ing in palm and sole (Ateles and the higher primates) it would 

 be difficult to establish the relative standing of hand and foot 

 with respect to discreteness of pads. The hypothenar divi- 

 sions, H d and H p , are more commonly separately recognizable 

 in palms than in soles. In palms H d is characteristically 

 lowered, while in soles the dermatoglyphic indications and 

 occasionally the pads themselves point to greater elevation 

 in H d than in H p . Pads Th and I of the palm usually are 

 fused, and when elevated in a common prominence the summit 

 is almost invariably centered in I. Soles commonly present 

 separate Th and I pads. 



Direct observation of pads admits the generalization that 

 in the adult the palmar pads are more conspicuous than are 

 those of the sole, as stressed above in reference to pads II, 

 III and IV. The dermatoglyphics provide a measure of the 



or* 



