176 Bulletin American Museum of Natural History. [Vol. X, 



Tarsus. — In the tarsus the case is different ; while the non- 

 serial Amblypod {Pantolambda) tarsus can be directly derived 

 from the Creodont, the serial Condylarth tarsus probably arose 

 from an unknown serial Creodont. Hence a double or parallel 

 derivation of the two-hoofed orders, as follows : 



Persistent atypi- Carpus second- Carpus and 



1^1 Otung^ulate cal displacement In arily serial. Tar- tarsus typically 



Creodonta. carpus and tarsus. sus persistently displaced. 



serial. 



Tarsus interlocking, \ Amblypoda. 



Carpus interlocking, f 1 ^77, 7 7~,-,7,7 



^ ., \ Londxlarthra. Diplarthra. 



1 arsus serial \ " ^ 



Other characters of the primitive foot are given in the following 

 synopsis, also upon pages 184, 187, 188, 216 of this Bulletin : 



2. — Synopsis of the Evolution of the Ambly- 

 poda. 



The subjoined table brings out the three important laws of 

 phylogeny as applied to taxonomy : 



First. — 'V\\Q persistent primitive characters {F.p.) are also the 

 ordinal characters., which serve to separate this phylum 

 from the Condylarthra, Proboscidia, Hyracoidea, Diplar- 

 thra and other ungulate orders. 



•^ 



Second. — The primitive {Pr.) progressive, {Pg.) and retrogres- 

 sive characters (Pe.) constitute the subordinal characters. 



Third. — Among the above characters are innumerable char- 

 acters both in skull, limb and foot structure in which the 

 Amblypoda parallel certain Perissodactyla, Artiodactyla 

 and Proboscidia. The latter are mainly approached in the 

 adaptations to great body weight, which first misled Cope 

 to place this group with the Proboscideans. 



