DERMATOGLYPHICS IN PRIMATES 107 



positions which have come to be regarded as typical centerings 

 of configurational fields. 



The accessory border fields IP and IV" are expressed in 

 three different relationships. They may appear as patterns, 

 or as discrete open fields separable from the adjoining border 

 configurational areas, or they may be considered absorbed by 

 expansion of these neighboring areas. Only in three genera is 

 II r in the form of a pattern, and that only as an occasional 

 occurrence Aotus, Gorilla and Pan. It is a separately 

 recognizable open field especially in Alouatta, Lagothrix, 

 Gorilla, Pan and Homo. IV" is characteristically patterned in 

 Aotus, and in Gorilla two of the eight hands are patterned. 

 The area of IV U is a separately defined open field especially 

 in Nycticebus, Lagothrix, Gorilla, Pan and Homo. In all the 

 remaining genera the expanse of interdigitals II and IV is 

 such that they encroach on the areas of IP and IV U , which are 

 thus absorbed either in a single open field or pattern. In 

 Nycticebus and Nasalis IV U is characteristically fused proxi- 

 mally with H d . 



Pattern elements in the distal portion of the central area 

 (2 P , 3 P and 4 P ) are characteristic in New World monkeys. 

 Aotus, with all three of these elements commonly expressed 

 (figs. 126-137), represents the extreme development of pat- 

 terns in this region. Generally they are much less consistent 

 in number, with only one or two of the patterns appearing 

 in a single hand, and even this partial expression is not as 

 frequent as in Aotus. Among the prosimians, Nycticebus 

 occasionally exhibits such patterns, but it must be noted that 

 while this region in the other forms does not present con- 

 tinuous epidermal ridges, there is a tendency especially in 

 Lemur (Mutrux-Bornoz, pis. 4 and 7) toward more marked 

 ridge formation in patches corresponding to the areas of 2 P , 3 P 

 and 4 P . Patterns 2 P , 3 P and 4 P occur sporadically in some Old 

 World monkeys (Pithecus and Pygathrix), and more com- 

 monly in Hylobatidae and in Pongo. 



The parathenar region, lying in the proximal part of the 

 central area, is separately definable in nearly all primates. 



