Hepburn — The Papillary Ridges on the Hands and Feet of Monlceys and Men. 533 



The eminence in the hypothenar region of the mandrill showed two features 

 worthy of interest ; first, the transverse direction of the ridges constituting the core 

 of the design, and, second, the interference with the full development of the 

 eminence on its ulnar or free border, resulting in the production of a series of 

 pyriform loops. Similar pyriform loops may be seen on the eminences at the 

 bases of the digits in PI. xlvii. 



On the thenar eminences, an interesting series of patterns was found. These 

 varied from simple, almost perfectly concentric ridges surrounding a short central 

 one, as in PI. xlviii., to a series of pyriform loops in the left hand of the same 

 animal, and an attempt to form two foci, as in PL xlix., which has only resulted 

 in the production of two sets of pyriform loops dovetailing into each other. 



The discussion of the papillary ridges on the palmar aspects of the digits will 

 be undertaken most satisfactorily by considering the phalanges separately. 



The first phalanx of each finger possesses a modified bulging eminence, and 

 the arrangement of its paj)illary ridges varies accordingly. The second phalanges 

 present the ridges in theii' simplest form, and on them the direction is mainly 

 transverse to the long axis of the digit, i. e. parallel to the long axis of any object 

 grasped in the hook-like manner characteristic of trapeze-movements (Pis. xlvi. 

 and XLIX.). 



On the first phalanges, the eminences are not so fully developed as those of the 

 palm and sole, and consequently the ridges present forms which are intermediate 

 between a transverse and a concentric arrangement. 



The terminal or ungual phalanges of all the digits possess marked bulbous eminences 

 on their palmar aspects, and on them the papillary ridges are modified to corre- 

 sjDond. The consideration of this group of ridges derives additional interest from 

 the fact, that, in man, the corresponding regions have been specially studied, in 

 whom, moreover-, the patterns have been shown to be so persistent as to afford a 

 reliable basis for establishing individual identity. 



It is well to note that the conditions provided by the terminal j)halanges differ 

 considerably from those prevailing in the regions of the palm or sole, where we 

 have already seen patterns located. In the first place, eminences in the palm or 

 sole are elevated areas rising out of a general flattened surface. Their growth and 

 expansion may be restricted by the presence of neighbouring similar elevations, 

 whereas the terminal phalanges are free at their extremities as well as on two 

 borders. The only restriction to the growth of papillary ridges is found at their 

 proximal end, where the abrupt flexures of the terminal articulations occm\ In 

 the second place, the development of a nail upon the dorsal aspect of each terminal 

 phalanx is, undoubtedly, an important factor in producing the elongated character 

 of the terminal phalanx, whose length is always greater than its osseous element 

 would lead us to expect. This series of conditions must also act as modifying 



TEANS. EOT. BTJB. SOC, N.S. VOL. T. , PAET X. 4 F 



