176 DINOCERATA. 



Returning now to the Amhli/daefi/la, or the group from which the 

 Dinocerata were evidently derived, and to wliich they belong, we may 

 safely assign to them general characters as follows : 



(1.) Brain, small and smooth. 



(2.) Teeth, not more than forty-four. 



(3.) Post-glenoid process. 



(4.) Odontoid process, conical. 



(5.) Cervical vertebrae, flat. 



(6.) Trunk vertebrfe, twenty-three or more. 



(7.) Scapula, acuminate. 



(8.) Feet, plantigrade. 



(9.) Five digits in manus and in pes. 

 (10.) Axis of foot through third digit. 

 (11.) Carpal and tarsal bones, somewhat interlocking, 

 (12.) Three bones in first tarsal row. 

 (13.) Astragalus, flat. 

 (14.) Fibula articulating with calcaneum. 

 (15.) Cuboid articulating with astragalus. 



From this group came off", evidently in the late Cretaceous, first the 

 CoryjjJiodonfia, having nearly all the above characters, and becoming 

 extinct in the early Eocene. The Dinocerata probably branched off" about 

 the same time, and survived to the Middle Eocene, thus becoming much 

 more specialized before their extinction. 



Classification of Ungulates. 



Accepting this general view of the origin of the Ungulates, living and 

 extinct, their classification has been outlined in the diagram on page 173, 

 and little more can now be done. 



The attempts hitherto made to give a detailed classification of all the 

 Mammalia, living and extinct, have signally failed, mainly because only a 

 small part of even the extinct forms now known were included, and almost 

 every new discovery tended to break down the definitions so systematically 



