1010.] The Condylarthra and Taligrada. 357 



Order Condylarthra Cope. 



Family Piienacodontib^. Examples: Basal Eocene Euprotogonia, 

 LoAver Eocene Phenacodu-^. Progressively cursorial, manus and pes becom- 

 ing tridactyl by reduction of digits I and V; lunar- unciform contact de- 

 creasing (Matthew), carpals flattening and carpus becoming serial; centrale 

 not free (Phenacodus), magnum large. Humerus with moderate entocon- 

 dyle and entepicondylar foramen. Scapula rounded superiorly, coracoid 

 process small. Astragalus with well developed trochlear keels; not touch- 

 ing cuboid; foramen early reduced or wanting. First and second u})per 

 molars cpiadrate, i. e., with well developed hypocone; cusps bunoid. P^ 

 triangular, with tritocone. M3 with small hypoconulid. 



Family Meniscotheriid^. Lower Eocene, Mcniscothcrium. Ambu- 

 latory; tridactyly less pronounced. Lunar- unciform contact not large, 

 carpals flattening (sub-serial), centrale free. Humerus with moderate 

 entocondyle and entepicondylar foramen. Coracoid process small. Astra- 

 galus not touching cuboid, trochlear groove slight, neck slender; astragalar 

 foramen variable. M^ m^ quadrate, with well developed hypo-, para- and 

 metacones and large protoconule, all crescentic; metaconule confluent with 

 hypocone. P^ ■ triangular, with tritocone ; protocone, tritocone and proto- 

 conule crescentic. ^Ig without hypoconulid ; metaconids on nij-nia re- 

 duplicate. 



Order Taligrada (Cope). 



Family Periptychid.e.^ Basal Eocene (r. g., Anisonchii.s, Ilaplo- 

 conus, Conacodon, Periptyckus). Ambulatory; pes {PeriptycJius) fully 

 pentadactyl (digits I and V hardly if at all reduced); manus not known. 

 Humerus with very stout entocondyle and large entepicondylar foramen 

 iPeripttjchus). Scapula pointed superiorly; coracoid process large. As- 

 tragalus broadly touching cuboid, trochlea very broad and convex, with 

 broad neck; or trochlea broad with low keels {Hemiihloeus koivalevskiamis 

 cf. ISIatthew, 1897, p. 297), large astragalar foramen. M', ni" triangular; an 

 anterior and a posterior basal cingulum sometimes rising into distinct cusps; 

 main cusps conic. P* bicuspid, tritocone wanting. Mg with or without 

 hypoconulid. 



Family Pantolambdid^e. Basal Eocene (Torrejon) Pantolambda. x\m- 

 bulatory; digits rather short, I and V not reduced; lunar-unciform contact 

 broad, centrale separate, magnum small. Humerus with stotit entocondyle 

 and entepicondylar foramen. Scapula pointed superiorly; coracoid process 



1 Regarded by Matthew as Condylarthra. 



