534 Hepburn — The Papillary Ridges on the Hands and Feet of Monkeys and Men. 



influences in determining the shape and dimensions of the bulbous projecting 

 eminence, or pad, which characterises the palmar aspect of a terminal phalanx. 



An examination of the papillary ridges covering the palmar aspect of a ter- 

 minal phalanx, therefore, resolves itself into two parts ; first, the arrangement of 

 the ridges where there is no raised area, and second, their arrangement where a 

 raised area is present. 



Where there is no raised area on the palmar aspect of a terminal phalanx there 

 is no outstanding design or pattern, because, as ah-eady seen, this is always asso- 

 ciated witli raised areas or eminences, but, on the other hand, the papillary ridges 

 are arranged transversely to the long axis of the phalanx. This is the condition of 

 the ridges on the terminal phalanx of man on the proximal side of the intersjmce 

 which encloses the pattern. On the distal side of the interspace the ridges are 

 again arranged transversely, but with a convexity towards the convex-rounded 

 free end of the phalanx to which they have adapted themselves. Of the monkey 

 impressions in my possession the only one which gives a distinct indication of this 

 arrangement is that of the right middle finger of the chimpanzee 

 (fig. 1). Allix* indicates this fact in one of his illustrations (pi. iii., 

 figs. 2 and 4). 



The elevated area on the palmar aspect of the terminal phalanx 

 presents a design or pattern corresponding to the shape of the 

 elevation. The ridges on the proximal and distal aspects of the 

 elevation are tranverse. Of course around the convex free end of the phalanx 

 the ridges become bent accordingly until along the lateral borders of the phalanx 

 the ridges are almost longitudinal. This change in the direction of the ridges 

 may be explained by the increase in the length as compared with the breadth 

 of the phalanx and the coincident elevation of an area in the long axis of the 

 digit. 



It is not difficult to understand how the transverse ridges situated proximally 

 might become separated from those characteristic transverse-convex ridges placed 

 distally by the gradual projection of a raised area between the two 

 sets of diverging transverse ridges so very distinctive of human 

 patterns. 



In none of my impressions from the lower monkeys are such 

 interspace patterns visible, but in the two from the chimpanzee, 

 showing the right index and medius, the interspace patterns are 

 distinctly introduced (figs. 1 and 2), and they very closely resemble specimens of 

 the looped designs figured by Galton. The apparent absence of interspace 

 patterns among my monkey impressions may very probably be due to the 



* Loc, cit. 



