DEEMATOGLYPHICS IN PRIMATES 117 



Cebus, where the ventral surface of the tail presents scantier 

 hair throughout the area corresponding to the dermatoglyphic 

 region of the three genera just named. In the zone of scanty 

 hair the skin surface may be readily observed, at least in the 

 newborn specimen examined. This grasping surface is marked 

 by a series of transverse skin folds which are progressively 

 narrowed proximo-distally. These corrugations, in a newborn 

 Cebus having a tail 19.5 cm. in length, are limited to the 

 distal 7 cm., where they gradually diminish in breadth from 

 3 mm. to 1.5 mm. The grooves separating the corrugations 

 extend to the lateral surface, becoming shallower until the 

 corrugations and the grooves disappear at about the middle 

 of that surface. In the ventral midline of about the distal half 

 of the tail there is a continuous shallow sulcus. 



It is to be emphasized that the transverse folds of the tail 

 in Cebus are not homologues of epidermal ridges; they may 

 be likened instead, both in anatomic and functional signifi- 

 cance, to the bulges on the flexor surfaces of digits. It is 

 apparent that the folds would be a mechanical aid in grasping, 

 through yielding and adaptation to the contours of surfaces. 



The longitudinal furrow in the midventral aspect of the 

 tail, mentioned only in the instance of Cebus, occurs also in 

 the tails of other forms, being a superficial indication of the 

 interval between the caudal flexors. In the monkeys which 

 bear caudal dermatoglyphics, the angle of the herringbone 

 configuration is aligned more or less regularly in this furrow. 



PATTERN INTENSITY 



The numerous illustrations of palms and soles (figs. 5-593) 

 provide a record of descriptive variations of the dermato- 

 glyphics, and* the tabulations accompanying them stand as 

 condensed descriptions. Such data, however, are not well 

 adapted to the tracing of resemblances and differences among 

 genera, between hand and foot and between right and left 

 sides, as well as among the several configurational territories. 

 Some quantitative approach more fundamental in nature than 



