358 Bulletin American Museum of Natural History. [Vol. XXVII, 



large (?). Astragalus broadly touching cuboid, trochlea broad, with low- 

 keels; an astragalar foramen. M^, nij triangular (without hypocone), with 

 small anterior and posterior cingula; para- and metacone strongly V-shaped, 

 mesostyle very prominent. P^ bicuspid, external cusp V-shaped, tritocone 

 wanting. M3 without third lobe. Size not large, skull hornless, with sagit- 

 tal crest. 



Order Amblypoda Cope. 



Family Coryphodontid^. Lower Eocene (chiefly Corijphodon). 

 Ambulatory; all digits very short, II-IV very broad, phalanges very short; 

 lunar-unciform contact retained ; unciform spreading upon digit III, 

 pushing magnum over on digit II. Humerus with entocondyle relatively 

 reduced and without entepicondylar foramen. Scapula pointed superiorly 

 but postspinous fossa produced backward. Astragalus very broad, troch- 

 lear surface extending down on front of neck, astragalus spreading over on 

 cuboid; astragalar foramen wanting or greatly reduced. Mj, ni, sub-triang- 

 ular, a prominent protoloph formed of the protocone and parastyle, para- 

 cone small, conic, metacone V-shaped. M3 without hypoconulid. Size 

 large, skull hornless (incipient frontal tuberosities in Coryphodon wortmani, 

 fide Osborn). Sagittal crest widening into a flat vertex. Canines elongate. 



Family Uintatheriid^. Middle Eocene {e. g., TJintatherium,, Loxolo- 

 pJwdon). Ambulatory; limb characters of the Coryphodontidiie all further 

 developed. Uj)per molars with strong protoloph (formed as in Cory- 

 phodonti(he) antl metaloph (probably representing a displaced paracone, 

 mesostyle and metacone — -fide Osborn, 1907, p. 167). M3 without hypo- 

 conulid. Size very large, skidl top finally with three pairs of bony pro- 

 tuberances on nasals, frontals and occiput respectively. Upper canines 

 sabre -like. 



The preceding brief analysis is sufficient to indicate that the Pantolamb- 

 did;e, Coryphodontidtie and Uintatheriida^ form an ascending series and that 

 the Periptychithe are connected on the one hand with this series at its base 

 and on the other hand with the Condylarth families Phenacodontidjie and 

 Meniscotheriidie. Osborn, who favors the phylogenetic, or vertical, system 

 of classification, observing that Peripfychus resembles the Amblypoda 

 rather than the Condylarthra in the possession of an astragalo-cuboid con- 

 tact and of "strictly trigonal molars" (/. c., p. 181) added the family to the 

 Taligrada and placed the latter with the Amblypoda as already stated. 



More in detail, apparent reasons for this phylogenetic grouping may be 

 stated as follows: 



Condylarthra (including only the Phenacodontida? and Meniscothe- 

 riidte). 



