182 MAMMALIAN DENTITION 



diminution in the sectorial character of this tooth began to 

 occur together with the appearance of a postero-internal cusp. 

 Other features were the corresponding diminution of the shear- 

 ing edge of the first lower molar and the transformation of 

 the first upper molar into subquadrate shape. Similar stages 

 to these are even now to be observed in the comparison of the 

 Cacomistle (Bassaris), the Coati (Nasua) and the Raccoon 

 (Procyon) (see Fig. 100) : the first shows a sectorial premolar 



Fig. 64. — Dentition of Coati-mundi (Nasua narica, 9,7425-4). Note the diminution of 

 sectorial features in the last upper premolar and first lower molar. 



with a fair shear and no postero-internal cusp, and a first up- 

 per molar narrow antero-posteriorly; the second, diminution of 

 the premolar shear with a small postero-internal cusp and a sub- 

 quadrate first upper molar; the third, a greatly transformed 

 premolar and a subquadrate molar. 



As an example of the family we shall take the Coati-mundi, 

 Nasua narica (Fig. 64) from tropical America. This is a gre- 

 garious beast, hunting in small troops and feeding upon fruits, 

 young birds, eggs, lizards and insects. Its dental formula is: 



