VERTEBRATA 



123 



The ToxoDONTiA are confined to the South and Central 

 American continents. They appear first in the Eocene of 

 Patagonia and continue through the Plistocene system. 

 These later representatives of the genus Toxodon reached 

 the size of the largest species of rhinoceros. The teeth are 

 lophodout, and early began to be prismatic, and to grow 



Fig. 68. — Dryopitheeus fontani Lart.; anthropoid ape from Middle Neo- 

 cene of France ; ramus of lower jaw, natural size. From Gaudry. 



from persistent pulps. This condition appeared first in the 

 incisors, some of which resemble somewhat those of ro- 

 dents, and later in the molars. There are two suborders of 

 Toxodontia which differ as follows : 



Femur with third trochanter ; a clavicle ; 

 Femur without third trochanter; no clavicle ; 



Typotheria. 

 Barytheria. 



The known species of Typotheria have five anterior, and 

 four or five posterior digits, and they are of medium and 



