322 [Nov. 1847. 



The Committee on Dr. Leidy's description of a new genus 

 and species of Fossil Ruminants, reported in favor of publi- 

 cation : 



On a new genus and species of fossil Ruminantia: Poebrotherium Wilsoni. 



By Joseph Leidy, M. D. 



Indirectly, through Mr. J. S. Philips and the influence of Dr. S. G. Morton, 

 the Academy has become the depository of a valuable and unique fossil, 

 received through Dr. S. D. Culbertson, of Chambersburg, Pa., from Mr. 

 Joseph Culbertson. 



As first received, it consisted of a mass of argillaceous limestone, having 

 one side of a cranium of an animal exposed to view, which, by the patience 

 of Dr. T. B. Wilson, was relieved of its matrix, and the lower extremity 

 of the humerus, and the upper extremity of the ulna and the radius of the 

 right leg were also disclosed. 



The top or vault above the orbits and posterior part of the cranium are 

 wanting, as are also the ossa nasi, 03sa intermaxillaria, the part of the os 

 maxillare inferius just anterior to the commencement of the symphysis, and 

 the zygoma of the left side, but sufficient is left to charcterize it as a remark- 

 able genus of Ruminantia, very different from any that has been heretofore 

 described. 



The cranium belonged to a full grown or adult animal, but not an old 

 one, as is indicated by the teeth. 



In the upper jaw are seven molars, differing in this respect from any 

 ruminant known, living or fossil. The posterior three molar3, usually called 

 true, present nothing very peculiar in their conformation. They are not so 

 square as in Cervus, but are more like those of Ovis, being much broader 

 than wide, so that they have a compressed appearance. The four crescents 

 upon the crowns are quite simple. Externally these teeth present two and 

 nearly plane surfaces, separated by an abrupt, salient, longitudinal ridge on 

 a line with the notch separating the anterior and posterior pair of columns. 

 Each of these surfaces has a longitudinal rounded ridge, more prominent 

 upon the anterior than the posterior one, but neither so salient as the first. 

 The antero-external border is also elevated or prominent, so that each of 

 these teeth presents externally four longitudinal ridges. As is usual, these 

 teeth are obliquely situated in the jaw, and the anterior part of one folds 

 over externally or overlaps the posterior part of the one preceding it. 



The anterior four molars or premolars are not more than half the length 

 of the true molars, and differ among themselves so as to render it necessary 

 to examine them separately. The posterior or fourth premolar has more the 

 characteristics of a true molar, and it would probably not be wrong to con- 

 sider it as an additional true molar. The crown presents four crescents, 

 which are thicker than in the true molars, and the anterior and posterior 

 pair are separated by a comparatively deeper notch. Externally the tooth 



