DERMATOGLYPHICS IN PRIMATES 105 



monkeys except Seniocebus and Saimiri, and, among the 

 catarrhines, Papio, Pithecus, Cercocebus, Colobus, Gorilla. 

 The genera in which separation of the two elements is evident 

 only occasionally are : Lasiopyga, Pygathrix, Symphalangus 

 and Homo. Another departure is the occurrence, in varying fre- 

 quency, of a pattern in the H p area which is not limited from 

 an open field extended into H d (as in fig. 589), occurring in: 

 Seniocebus, Oedipomidas, Callithrix, Aotus, Ateles, Cebus, 

 all Old World monkeys except Cercocebus, Hylobatidae, Pan, 

 Homo. A reversal of this situation occurs in Perodicticus, 

 where it is H d instead of H p which is patterned (figs. 25-26). 

 Finally, there is the condition in which a pattern lies at an 

 intermediate level (as in fig. 115) or in which there is a con- 

 tinuous open field (fig. 581) as an indication of more intimate 

 fusion of H d and H p . Such configurations occur sporadically 

 among genera in all the groups except Old World monkeys. 

 With the exception of examples in this last category, it will be 

 clear that the two elements of the hypothenar region are char- 

 acteristically distinct, since their identities are topographi- 

 cally separable even in the absence of a boundary line between 

 a pattern in one and an open field in the other. 



The thenar and first interdigital areas call for joint discus- 

 sion on account of their frequent merging. These two con- 

 figurational fields are characteristically separate in pro- 

 simians, though in Tarsius and Lemur there are cases 

 presenting departures of the types characterized below. In 

 Callithrichidae they are invariably separate. Among the 

 genera of Cebidae and catarrhines, as well as within a 

 single genus, there is variable behavior of Th and I. In all 

 these genera, excepting Magus (only two hands available) and 

 Erythrocebus (six hands), at least some individuals present 

 independent configurations of the two areas. Such inde- 

 pendence varies in frequency among the genera, being es- 

 pecially common in Alouatta, Aotus and Pygathrix, where the 

 majority of hands are so distinguished. In about half the hands 

 in Pithecus and Pan Th and I are separate. Smaller fre- 

 quencies of the condition occur in Saimiri, Ateles, Cebus, 



