70 



MAMMALIAN DENTITION 



\Ye shall now proceed to the consideration of the dentition 

 of the Marsupialia as a study in the adaptation of tooth forms 

 to life habits. As a standard a fairly primitive type of animal 

 must be taken. It must fulfill at least many of the require- 

 ments already laid down: thus it will be of small size, of in- 

 sectivorous (or insectivorous-omnivorous) diet and of terres- 

 trial or arboreal habit. 



An animal fulfilling the foregoing requirements is the tiny 



Fig. 17. — Occlusal view of dentition in Marsupial Mouse (Phascologale flavipes, 

 9.211-2). Compare the upper molars with those of Dryolestes (Fig. 16) and the lower 

 molars with those of Amphitherium (Fig. 15). The scale in this as in all succeeding 

 illustrations indicates millimeters. 



Australian Marsupial Mouse (Phascologale flavipes). A glance 

 at the photograph (Fig. 17) shows the marsupial character 

 in the fenestrated palate, the inflected mandibular angle and 

 participation of the malar bone in the glenoid fossa. The tooth 

 formula is: 



i|,c{,p|,Mi 



total 46. 

 The incisor toavs approaching each other obliquely, the well 



