PRIMATES FEOM MADAGASCAE. 159 



(2) Madagascar has been joined to the mainland for a lengthened period at a later 

 date, possibly as late as the Miocene epoch. 



(3) There is strong presumptive evidence that on this southern land-mass there was 

 during the Eocene period a race, or races, of Primates whicli had already acquired most 

 of the distinctive Simian characters. This evidence is two-fold : (a) In the Oligocene 

 of Santa Cruz several genera of well-differentiated Cebida3 have been found, (b) By 

 the Miocene epoch the Simian stock on the African Continent had already produced 

 many highly developed forms, having all the chief features of the Old World Monkeys. 

 The inference is strong that the race or races of Primates isolated in Madagascar at 

 the time of its severance from the mainland would already have acquired most of the 

 characteristic features of the " Anthropoidea." 



(4) This ancestral Malagasy stock might, at the time of its isolation, be expected to 

 have certain characters showing its affinity with both the Cebidse and the Old World 

 Monkeys. 



(5) The subsequent history of these Malagasy Primates has apparently been one of 

 arrested development or actual retrogression so far as the condition of the brain is 

 concerned *, while adaptive modifications have arisen in most of the genera tending 

 still further to disguise their pithecoid affinities. 



It will have been noticed in the preceding descriptive sections that Avhile in the 

 main the affinities of these recently-discovered Malagasy fossils are with the Primates 

 of South America, there are, nevertheless, certain features which find their closest 

 analogy in various Old World forms. Thus the strong large vertical upper incisors of 

 Archmolemur are almost identical with those of various African genera (see text-figs. 

 11 & 12). It may be said that this is merely a case of convergence, but it seems to 

 me more probable that the primitive Indrisine stock all possessed these strong upper 

 incisors. It is not very easy to conceive how Chiromys, if it had originally only the 

 weak incisors of modern Lemurs, should have developed the very large and strong 

 rodent-like teeth which at present characterise it. 



In text-fig. 52 some of the results arrived at in the foregoing comparative survey are 

 shown in diagrammatic form. On the two sides of the figure many of the so-called 

 Anthropoid and Lemuroid characters are contrasted, and by the varying proportions of 

 the black and tinted areas under the names of the different genera an attempt has 

 been made to indicate the extent to which the various characters are present in these 

 typical forms. Where a " Lemuroid " character is present in some one or more genera 

 of Old or New World Monkeys, this has been shown in the two right-hand columns of 

 the diagram, and the accompanying numerical references indicate where such character 

 has been observed. It is very noticeable how many of these so-called Lemuroid 



* Note. — The cerebral degeneration of such forms as Falceoioropithecus and Megaladcqns of course implies 

 a ■previous evolution to that higher state from which they have degenerated. It seems more reasonable to 

 suppose that this previous evolution should have taken place under very different conditions from those which 

 have produced the subsequent retrogression and also at a much earlier date. 



