NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 75 



The lower dentition of Protylopusf annectens is characterized by a 

 small but distinct metaconid on the posterointernal crest of P*. The 

 entoconid of the lower molars is conical as in Protylopus petersoni, 

 and likewise the valley between the entoconid and hypoconid is open 

 lingually through a small pocket formed by the anterior crest of 

 hypoconid and a metastylid crest on the posterior surface of the meta- 

 conid. However, the anterior surface of the metaconid is different in 

 that it is smoothly conical and lacks the anterior spur or crest which 

 joins the anterior wing of the protoconid in the earlier form. In P.f 

 annectens the parastylid or anterior wing of the protoconid swings 

 widely forward around the metaconid so that the valley between the 

 metaconid and protoconid is also open lingually. In P. petersoni and 

 in lower molars believed to represent Oromeryx pUcatus, this valley 

 is closed forward and an anterior cingulum is carried around the tooth, 

 rising on the lingual side of the metaconid so as to form a small pocket 

 on the anterolingual surface of this cusp. It is further noted that a 

 marked hypoconulid is developed on the posterior extremity of the 

 crest from the hypoconid in Mi and Ms, perhaps better defined than 

 in the earlier forms, and the lingual cusp on the hypoconulid of M3 

 has nearly or entirely lost its identity in the horseshoe-shaped crest 

 of the hypoconulid lobe. 



Genus CAMELODON Granger, 19 10 



Type. — Camelodon arapahovius Granger, 19 10. 



Discussion. — The teeth in this form, as far as can be determined 

 considering the advanced wear exhibited in the only known specimen, 

 are rather like those in Protylopus, but with smoother enamel. The 

 principal character distinguishing Camelodon is the marked diastema 

 between P2 and P3. Camelodon would appear to represent an aberrant 

 stem within the Oromerycidae, not ancestral to Eotylopus. It should 

 be noted, moreover, that the diastema in the lower premolar series of 

 Poebrotherium is anterior to Pg. 



CAMELODON ARAPAHOVIUS 39 Granger, 19 10 



Type.—Leit ramus of mandible with P2-M3, A.M. No. 14604. 



H orison and locality. — Uintan equivalent of the Wagonbed deposits 

 on Beaver Divide, Fremont County, Wyo. 



Discussion. — In size Camelodon arapahovius is about intermediate 

 between Protylopus petersoni and Protylopusf annectens. Neither of 



39 Illustrated in Granger, 1910, fig. 4; and Scott, 194S, pi. 2, fig. 2. 



