82 r>E. H. p. STANDING ON SUBFOSSIL 



■vertical direction and occupying a position just internal to the postglenoid process. 

 Its inferior wall is much thickened. This shallow chamber apparently represents the 

 vestigial auditory bulla. There is a curious massing together and proliferation of the 

 parts around the meatus, forming a tube of more than 1 cm. in length. An irregular 

 and variable mass of bone is, in fact, always present in this region produced by the 

 anchylosis or close apposition of the following elements : — the postglenoid process, the 

 external margin of the tympanic, the mastoid process, and the paroccipital process. 

 This mass of bone is pierced by the stylo-mastoid foramen and the postglenoid foramen. 

 The actual margin of the external auditory meatus is formed by the petrous portion 

 of the squamosal and by the tympanic. 



The Dentition of PalEeopropithecus, (Plate X.) 

 As already stated, the dental formula oi Palmopropithe^us maximus corresponds with 

 that of Indris, Frojnthecus, and Avahis. A detailed comparison with these three genera 

 shows that in several particulars Propithecus exhibits the closest analogy with the 

 fossil form. We may instance specially the shape of the premolars. The median pair 

 of incisors are much larger than the lateral. Both pairs are cylindrical in section. 

 The inner pair are curved towards each other at their lower extremity. Their worn 

 surfaces show that all four have been apposed to the extremities of the lower 

 incisors as in Archmolemur. The inclination of both upper and lower incisors bears 

 a close resemblance to the condition seen in some of the Platyrrhine Monkeys 

 (e. g. Pitheciu) (text-fig-. 12). 



The canines are triangular in section, presenting a strong anterior ridge which is 

 separated by a deep groove from a broader internal ridge. A small posterior cusp is 

 present, as in all the extant representatives of the subfamily. The anterior premolar 

 does not differ materially from the corresponding tooth of Propithecus, except that it is 

 narrower in a transverse direction. The whole series of molars and premolars is in 

 fact decidedly narrower than in any of the recent forms. The anterior premolar is 

 constricted near the centre of the lingual margin, thus being divided into a narrower 

 anterior and a broader posterior portion, the same feature being seen to a less degree in 

 the posterior premolar. The second premolar bears a very small cusp on its inner 

 margin, the homologue of which is traceable in Propithecus. The anterior ridge of 

 this tooth curves outwards to join the external cingulum, but without giving rise to a 

 pointed cusp as in Propithecus. The strongly developed anterior and middle labial 

 cusps of Propithecus are represented in Palceopropitheciis by slight elevations of the 

 external cingulum. In the first molar the internal cusps are not subequal as in the 

 recent genera, but the anterior one is greatly in excess of the posterior both in height 

 and length. The same is true of the second molar, though here the extant Indrisinte 

 bear some resemblance to the fossil form. This flattening down and reduction of the 

 postero-internal cusp of the molars is of special interest, as indicating a transition to a 



