DERMATOGLYPHICS IN PRIMATES 



error of stating-, as if no other form were comparable: "Of 

 course its highest development is found in the hand and 

 foot of man." The prosimians as a group exhibit a lesser 

 expanse of ridging, here, as in the marsupials, largely con- 

 fined to the pads. From the marsupials, genera could be 

 selected to match closely the conditions in prosimians. Some 

 insectivores, rodents, edentates and carnivores possess epi- 

 dermal ridges, but their occurrence is sporadic in these orders 

 rather than characteristic. 



Our observations on the extent of ridged skin in primates 

 agree in principle with those of previous workers, including 

 ridge formation on the tails of Alouatta, Ateles and Lagothrix. 



The prosimian genera are widely diverse with respect to 

 the extent of ridge formation. In the six genera represented 

 in our observations Galago shows the least extensive ridge 

 formation ; definitely formed ridges are confined to the apices 

 and slopes of the pads, while elsewhere on the palm and sole 

 the epidermis is studded with islands or with consolidations 

 of these units forming the "Warts" of Whipple. Progressive 

 expansion of the ridged area is to be seen in Perodicticus, 

 Daubentonia and Tarsius. In Lemur the extension has pro- 

 ceeded still further. The patches of ridged skin characterizing 

 the central portions of the palm and sole are larger than in 

 the genera just mentioned, and their component ridges are 

 consistently aligned (admitting the tracing of general ridge 

 directions through these regions, as illustrated in figs. 33-40). 

 Except in flexion furrows and in an occasional palm showing- 

 deficient ridge formation in a portion of the central area, 

 Nycticebus presents continuously ridged palmar and plantar 

 surfaces. 



All the genera of Nycticebidae which we have studied are 

 included in Hill's rating of progressive specialization in this 

 family (Lorisoids, Hill). He ranks Loris as the most primi- 

 tive, and in order follow Nycticebus, Perodicticus, Galago. 

 Our observations on the extent of ridged skin do not correlate 

 with this order. Nycticebus is more advanced than Loris in 

 having a complete covering of ridged skin in the foot, and 



