78 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I28 



which was generally accepted as camelid, along with certain other 

 Eocene forms now also included in other families. Subsequent studies 

 have included description of Camelodon by Granger in 191 o, here 

 assigned along with Protylopus to the Oromerycidae, and description 

 of the Duchesnean Poabromylus by Peterson in 1931, which I believe 

 should be regarded as a leptomerycid, closely related to Leptoreodon. 

 The new form Poebrodon, the description of which follows, thus 

 would seem significant as perhaps the first true camelid to be known 

 from the Eocene. 



Discovery of the rather limited material representing Poebrodon 

 has given new evidence as to the phylogenetic arrangement of certain 

 of the Eocene selenodonts and has further emphasized the necessity 

 for designating the new family Oromerycidae. Protylopus was early 

 looked upon, particularly by Wortman (1898) and Scott (1899), as 

 being in an ancestral position within the Poebrotheriinae, although 

 Matthew (1910) suggested that this relationship applied only to the 

 descent of Eotylopus. Matthew went still further and excluded 

 Protylopus and Eotylopus from the Camelidae and suggested that 

 Poebrotherium was derived from "an advanced contemporary (to 

 Protylopus) genus of more northern habit." Peterson, like Scott, re- 

 tained Protylopus in the Camelidae but agreed with Matthew that the 

 ancestry of Poebrotherium was to be sought "in some more advanced 

 contemporary genus." It was evident, however, that he thought this 

 would be found in the Uinta Basin ; a prediction that has been made 

 good. Scott (1945), however, remained convinced that Protylopus 

 gave rise to Poebrotherium as well as to Eotylopus. 



Discovery of Poebrodon, distinctly precocious, now furnishes the 

 form, in support of Matthew's and Peterson's views, that completely 

 anticipates Poebrotherium in its combination of characters, as far as 

 known. It likewise gives further evidence of the separateness of the 

 oromerycids from the camelids. 



P0EBR0D0N,*2 new genus 



Type. — Poebrodon kayi, new species. 



Generic characters. — Teeth like Poebrotherium but shorter crowned. 

 Anteroposterior^ much-compressed styles of upper molars slightly 

 more outstanding. Weak metastylid flexure on lingual wall of lower 

 molars, and lingual surface of metaconid and entoconid slightly more 

 convex than in Poebrotherium. Hypoconulid lobe of M3 with lingual 

 portion less reduced than in Poebrotherium. 



*2From Greek if^n ('^^a), grass; /3p<5w, to eat; and 'oStiv, tooth. 



