PEIMATES FROM MADAGASCAR. 



153 



That a vertical occiput and heavy mandible may even in a Monkey be associated with 

 long stout zygomata is seen in the case of the " Howlers " of South America (text- 

 fig. 46, A). 



The Basilar Begion. — The presence of prominent auditory bullae on the base of 

 the skull is considered by some writers as a distinctive Lemuroid feature, but in 

 Palceopropithecus this character is entirely absent. As previously stated, this is 

 probably a secondarily acquired character, and cannot be urged as an argument for 



Text-fis. 49. 



Front view of skull and mandible of Nyctiplthecus, showing large 

 Lemur-like orbits (c/. text-fig. 16). 



specially connecting Palceojwojjithecus with the Cercopithecidse and higher Apes. But 

 in Megaladapis the bullae are by no means prominent ; and since the two American 

 families both exhibit this feature it can hardly be urged as a peculiarity of the 

 Lemurs. 



The Mandible. — Several characters of the mandible of Archceolemur and Mesopro- 

 pithecus have been referred to in the detailed description of these fossils as allying 

 them with the Apes, and need not here be recapitulated. Reference should be 

 made, however, to one or two features urged by Milne-Edwards and Grandidier as 

 differentiating the mandible of the Indrisinse from the higher Primates. They state 

 that the coronoid process is much higher than the condyle. This is of course true in 

 the case of the three existing genera; but a comparison with the mandibles of the 

 various fossil relatives of the Indrisinae and with the American Monkeys shows that 

 this character cannot be relied upon as a diiferentiating feature distinguishing between 

 the Malagasy Lemuroids and the Monkeys (text-fig. 50). 



The Dentition. — The definite association of the recent IndrisintB through Mesopro- 

 pithecus with the Archaeolemurinae disposes of many of the objections raised against 

 the Simian affinities of the extant genera, since the dentition of Archceolemur and 

 Iladropithecus is distinctly Ape-like in character. It is just on the question of the 

 dentition, however, that there seems least prima facie reason for maintaining the 



