PEIMATES TEOM MADAGASCAE. 



113 



There are considerable variations in the shape and pattern of the molars. In some 

 specimens the posterior margin of the third molar is nearly straight, the tooth thus 

 having a distinctly triangular form. In other cases this margin shows a distinct 

 tendency to the development of a postero-internal cusp (see Plate XXVI.), thus giving 

 to the tooth an irregular rhomboidal outline. The backward extension of the dental 

 series also varies greatly. In some skulls the centre of the posterior margin of the 

 palate reaches almost to the second molar, while in other specimens the palatal margin 

 is posterior to a line joining the hinder edges of the third molars. 



Some of the crania show a curious lateral torsion of the long axis, the facial portion 

 being deflected to the extent of several millimetres from a line bisecting the posterior 

 part. This peculiarity is well seen in the skull figured on Plate XXVI. 



In his memoir on Megaladapis madagascariensis Forsyth Major says, " it is to be 

 anticipated that skulls of young specimens will bear a much closer resemblance than 

 the adult to the existing Lemuridse " ; and he instances several particulars in which 

 this will probably be the case, viz., a more rounded cranium, a brain-cavity relatively 

 and possibly absolutely larger than in the adult, a relatively shorter facial portion, and 



Text-fig. 26. 



Profile of cranium and mandible of young specimen of Mecjaladapis grandidieri. x g. 



the absence of postorbital prolongation of the frontals. He also anticipates that the 

 constriction of the olfactory fossa, due to the development of aerial sinuses (so marked 

 a feature of the adult) will be wanting in the young animal. 



The occurrence of a quite young specimen of Megaladapis grandidieri among the 

 fossils exhumed at Ampasambazimba makes it possible to test the validity of these 

 forecasts. In the skull in question the permanent canine and the second molar have 

 not yet appeared below the alveolar margin, but are visible deep in their sockets. 



A reference to the figure of this skull (text-fig. 26) will show that in its general 

 aspect it conforms much more nearly to the type of modern Lemurs than is the case 

 with the adult. The brain-case is rounded and relatively much more voluminous. 



