1 86 Bulletin American Museum of Natural History. [Vol. X, 



by astragalar foramen which issues posteriorly between the ectal and sustentacu- 

 lar facets (Fig. 12) (as in Creodonta). Astragalo-navicular head broad convex ; 

 two astragalo-calcaneal facets only. Fifth metatarsal curved with a prominent 

 external tuberosity for \ht peronetis brevis muscle, as in the Bear. 



All these osteological characters are shared by Periptychus, so far 

 as the skeleton of the latter genus is known ; (the carpus of 

 Periptychus is unknown). The skull, vertebrae and proportions of 

 the limb bones in the two types are remarkably similar. 



Ordinal or Amblypod Characters. — Primitive ordinal 

 characters. It will be observed in the definition of the Ambly- 

 poda, p. 180, that many of these above-described primitive charac- 

 ters persist throughout the evolution of the order, and therefore 

 rank as ordinal. 



Measurements : Skull, Teeth, Skeleton. 



Specialized Ordinal Characters. — There are, however, 

 many structures in Pantolambda which amply affirm Cope's view, 

 that Pantolambda is the ancestral type of the great lower and mid- 

 dle Eocene forms. These are : the separation of the preraaxillaj 



