J 82 Biilletiu American Museum of Natural History. [Vol. X, 



the Condylarthra) with little or no tendency to acquire the molar 

 pattern, is essentially similar in the two families. 



Subfamily Anisonchin^ O.slE. Subfamily Periptychin^ O.&E. 



Smaller forms. ? Arboreal. 1 Larger forms. ? Terrestrial. 



Superior molars with conules sup- Superior molars well developed, 

 pressed or wanting. Paraconid Paraconid strong, 

 reduced or wanting. Astragalus i Astragalus with shallower trochlea.'^ 

 short and wide,' with deeper troch- 

 lea. 



The genera and species of Periptychidse, as recently revised by 

 Matthew/ are given in the following geological table. 



UlNTATHERIID^ 



Bathyopsidtk . . 



CORYI'HODONTIDiE . 



PANTOLAMBDID/E. 



Pantolambda cavirictus. . . 

 " bathmodon.. 



Periptychid^. 



Ectoconus ditrigonus 



Periptychus rhabdodon .... 



" carinidens 



" coarctatus ..... 

 Conacodon entoconus 



" cophater 



Haploconus lineatus 



• " corniculatus. . . . 

 Anisonchus sectorius 



" gillianus 



Hemithloeus kowalevskianus 



Incert.*; Sedis. 



Ectoconodon 



Synconodon 



Protolambda 



Creta- 

 ceous. 



Basal 

 Eocene. 



Lower 

 Eocene. 



X 



Middle Eocene. 



Bridger. 





X 



1 Matthew, Bull. Am. Mus. Nat. Hist., 1897, p. 297. 

 - Op. cit., p. 265. 



