NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 21 



CAMELIDAE, AGRIOCHOERIDAE, OROMERYCIDAE, HYPER- 

 TRAGULIDAE, and LEPTOMERYCIDAE. 



Upper molars with distinct protoconule: Homacodon, Microsus, Antiacodon, 

 Bunomeryx, Pentacemylus, Mytonomeryx, Helohyus, Diacodexis, Wasat- 

 chiaf, Bunophoriisf, Protoreodon (except one species), and Diplobunops. 



Upper molars with weak protoconule, nearly lost in loph with protocone : Meso- 

 meryxf, Hylomeryx, Simimeryx, and Protoreodon (one species). 



Upper molars without protoconule: Achaenodonf, CAMELIDAE, OROME- 

 RYCIDAE, and LEPTOMERYCIDAE. 



P4 with metaconid distinct: Bunomeryx, Hylomeryx (late), Pentacemylus, My- 

 tonomeryx, Microsus, Hexacodus (in part), Antiacodon, Protoreodon, 

 Diplobunops, and Leptoreodon. 



P4 with metaconid weak: Hexacodus (part), Hylomeryx (early), and Poa- 

 bromylus. 



P4 with posterointernal crest instead of metaconid: Protylopus and Lepto- 

 tragulus. 



P4 without metaconid: Homacodon, Helohyinae, Diacodexinae, and Simi- 

 meryx. 



Lower molars with emphasized styles lingually on metaconid and entoconid: 

 AGRIOCHOERIDAE. 



Lower molars with moderate styles on metaconid but subdued or absent from 

 entoconid: OROMERYCIDAE, Simimeryx, and Leptotragulinae. 



Lower molars without or with but feebly developed lingual styles : Homaco- 

 DONTiNAE, Helohyinae, Diacodexinae, and Poebrotheriinae. 



Lower molars with parastylid on anterior crest of metaconid: Protylopus (early 

 stages), Oromeryx?, Camelodonf, AGRIOCHOERIDAE, and Leptotra- 

 gulinae. 



Lower molars with parastylid from anterior crest of protoconid: Protylopus 

 (later stages). 



Lower molars with paraconid placed close to metaconid, possibly developed by 

 twinning: Microsus (Mi and possibly other molars), Hexacodus, Antiaco- 

 don, Diacodexis, Wasatchia, Helohyus, Lophiohyus, and Parahyus (Mi). 



Lower molars without paraconid or parastylid: Homacodon (possibly on M3?), 

 Bmwmeryx, Hylomeryx, Pentacemylus, Mytonomeryx, and Poebrodon. 



Lower molars with crescentic outer cusps, but distinct median pocket developed 

 by forward direction of anterior crest of hypoconid. Entoconid united for- 

 ward with crest only to metaconid : AGRIOCHOERIDAE and Simimeryx. 



Lower molars with crescentic outer cusps, but distinct median pocket opens 

 lingually posterior to the metastylid. Entoconid isolated forward : OROME- 

 RYCIDAE. 



Lower molars with crescentic outer cusps, but anterior crest of hypoconid as 

 well as posterior crest of protoconid directed lingually. Entoconid united 

 foward by crest only with metaconid : Leptotragulinae. 



Lower molars with crescentic outer cusps, but anterior crest of hypoconid as well 

 as posterior crest of protoconid directed lingually and united separately with 

 entoconid and metaconid, respectively. Entoconid united forward by crest 

 to metaconid as well as to hypoconid: Poebrotheriinae. 



Lower molars essentially bunodont with no significant crest between metaconid 

 and entoconid : Homacodontinae, Helohyinae, and Diacodexinae. 



Ml and Mj with pronounced hypoconulid developed from cingulum and posterior 

 to saddle between hypoconid and entoconid: Homacodontinae. 



