MAMMALIA. 



CHAPTER I. 



DESCRIPTIONS OF UNGULATA PARIDIGITATA. 



Fam. 1, — RUMINANTIA. 

 Gen. POEBROTHERirin, Leidy. 



Poebrotherium IVilsonii, Leidy. 



(Plate I. Figs. 1-4.) 



Poebrotherium Wilsonii, Leidy: Proceedings of the Academy of Natural Sciences of Philadelphia, 1847, III. 

 322; Owen's Rep. of a Geol. Surv. of Wise, etc., 1852, 571. 



Poebrotherium is a peculiar genus of ruminants, among recent animals most 

 nearly allied to the Musks, and probably belongs to the second sub-family according 

 to the characters before indicated. 



The species Poehroilierium Wilsonii was established upon the greater portion of a 

 skull, which was the first mammalian fossil, sent to the Academy of Natural 

 Sciences of Philadelphia, from the eocene beds of Nebraska. It was presented 

 by Mr. Alexander Culbertson, of Chambersburg, Pennsylvania, and, when first re- 

 ceived, excited great interest among the members of the Academy, as being an 

 indication of the rich palseontological treasures since derived from the same locality. 



The specimen has lost the symphysis of the lower jaw, the end of the nose, one 

 zygoma, the upper part of the face, and the upper and posterior part of the 

 cranium. It is also much fractured and fissured; but the portions of it which 

 remain appear to have very well retained their original relative position. 



It belonged to an individual just reaching adult age; the permanent true molars 

 having protruded, but none of the deciduous molars having been shed. In the 

 upper jaw the molars are preserved on both sides, but several of those upon the 

 left side are broken. This series consists of the three permanent true molars and 

 three deciduous molars in a continuous row, and the first permanent premolar 

 separated by a hiatus from the others. (PI. I. Figs. 1, 3.) In the lower jaw, on the 

 left side, are preserved five, and on the right side six teeth, viz., three permanent 

 true molars, and three deciduous molars, forming a continuous row. (Figs. 1, 4.) 



