DERMATOGLYPHICS IN PRIMATES 129 



drops sharply to 0.18 and thus presents a singular low value 

 in the midst of an otherwise consistent trend of high intensity 

 to which all other monkeys adhere. Among the great apes 

 a progressive drop in pattern intensity is to be noted in pass- 

 ing from Pongo (0.96) to Gorilla (0.49), to Pan (0.31), that 

 drop being carried still further in man (0.21). 



The thenar area (Th) presents an average intensity of 0.29. 

 Fluctuations among the genera are marked, ranging from 

 to 1.00 and without orderly relations in the systematic 

 groups. 



In the first inter digital area (I) the average value is 0.72. 

 The general trend of high intensity is broken by abrupt de- 

 pressions in certain genera: Tarsius, 0; Lemur, 0.48; 

 Oedipomidas, 0.54; Callithrix, 0.56; Ateles, 0.41; Hylobates, 

 0.35; Gorilla, 0.20; Pan, 0.33; Homo, 0.10. In man the true 

 value would be less than 0.10, since in the routine formulation 

 of human palms an exact distinction between Th and I often 

 can not be made. 



The second inter digital area (II) has an average value of 

 0.76. In keeping with this highest value of all interdigital 

 areas, the majority of the genera show values of 1.00 or 

 values not much below 1.00. Minimum intensities occur in 

 Tarsius, 0; Hylobates, 0.02; man, 0.04. In great apes the 

 pattern intensities, though below the average recorded for 

 non-human primates, are much higher than in man: Pongo, 

 0.61; Gorilla, 0.44; Pan, 0.45. 



The third interdigital area (III) presents the lowest average 

 value of all the interdigital areas, 0.64. High values char- 

 acterize Lasiopygidae and Cebidae, excepting Ateles (0.04) 

 and Lagothrix (0.40). Callithrichidae have relatively low 

 values (Oedipomidas, 0.54; Callithrix, 0.30). Prosimians and 

 great apes are noteworthy for the dispersion of values within 

 the groups. In prosimians the intensities range from to 1.00, 

 and in gibbon and great apes the intensities are : Hylobates, ; 

 Pongo, 0.11 ; Gorilla, 0.84 ; Pan, 0.19. The value in man is 0.31. 



The fourth interdigital area (IV) has an average value of 

 0.74. Only Tarsius (0.03) and Hylobates (0.01) have values 



