LIFE HABITS AND DENTITION 77 



has long ears and silky fur but a long tail with a crest of hair 

 on the dorsal surface. The tooth formula is: 



i|,Cj,p|,m|. total 48. 



The jaws are elongated and associated with this feature is 

 the retention of the primitively large third premolar. 



The upper incisors, five in number on each side, also repre- 

 sent a stage as primitive as that of the American Opossum. 

 Although they and the lower incisors retain the insectivorous 



Fig. 21. — Dentition of Rabbit Bandicoot (Thalacomys minor, 9.213-1). This is a 

 very specialized form of omnivorous dentition. It is also one of the extremely rare 

 instances where a cusp (the metacone) has apparently migrated. The elongation of the 

 body of the third lower molar (one form of hypsodonty) is very clearly shown. 



arrangement and the latter are also somewhat procumbent 

 the crowns are flattened laterally and increase in antero-pos- 

 terior length. 



The canines present the great length usual in primitive 

 Mammals. 



The molars are quadrituberculate teeth adapted for grinding 

 rather than for shearing insects or flesh. Unfortunately the 

 dentition is somewhat worn in the specimen figured and 

 some cusps are not so clear as could be wished. By tracing their 



