608 THE PRIMATES xxm. 3- 



this procedure. Recognition that many of the surviving stocks have 

 been separate for a long time has led systematists to emphasize the 

 distinctions between the groups more sharply. Thus lemurs, far from 

 being regarded, as they were formerly, as rather primitive monkeys, 

 are now often placed in a distinct order, having in common with other 

 primates only 'the retention of certain primitive characters and an 

 adaption to arboreal life' (Wood Jones). There is no general agreement 



Fig. 384. Ring-tailed lemur, Lemur. 

 (From life.) 



about the best means of classification; the more traditional schemes, 

 such as that adopted here, probably give an over-simplified idea of a 

 progression of forms. A classification on more 'natural' or phyletic 

 lines could be devised, but would necessitate the postulation of a large 

 number of distinct categories, unless these were simplified by admitting 

 speculations about the affinities of the lines. 



We shall, as usual, in the main follow Simpson. His arrangement 

 retains the order Primates and recognizes two great suborders, 

 Prosimii and Anthropoidea. The division is 'horizontal' rather than 

 'vertical'; the two groups are not separate and divergent lines, they 

 contain respectively the ancestral and the 'developed' forms. Two 

 primate stocks are indeed known to have existed in the Palaeocene 

 and these are both included in the prosimians, whereas no anthro- 

 poids are known before the Oligocene. The Prosimii includes three 

 sorts of primate, all 'primitive' in the sense of retaining insectivoran 

 characters, such as long face, lateral eyes, and small brain; they are 

 grouped here as three infraorders: Lemuriformes for the lemurs of 



