110 ON THE EXTINCT MAMMALIA OF 



O. Culbertsoni. O. gracilis. 

 Circumference of shaft of femur at middle, . . . 24 lines. 



Diameter of head of femur at middle, . . . . 10 " 6 lines. 



Breadth of head together with great trochanter, . . 22 " 12 " 



Breadth of distal end, . . . . . 17 " 



The tibia and fibula of Oreoclon appear to have held the same relations of develop- 

 ment and form in comparison with those of the Hog as in the bones of the fore-arm. 



The breadth of the head of the tibia in different specimens pertaining to 0. Culbert- 

 soni ranges from fifteen to twenty lines. The breadth of the lower end in several 

 specimens, about ten and a half lines; in a specimen belonging apparently to 0. 

 gracilis, eight lines. 



The jiatella, calcaneum and astralagus of Oreodon are almost repetitions in form of 

 those of the Peccary. 



Of other bones of the hind foot of Oreodon, I have not had the opportunity of 

 inspecting any, but we may safely infer that they bear the same resemblance to those 

 of the Hog that those of the fore foot do. 



The relative lengths of the bones of the metacarpus referred to Oreodon resemble 

 in some respects the condition in the Tapir more than in the Hog. Thus, as in the 

 former, the first is longer and more robust than the fourth, and the second is pro- 

 longed inferiorly beyond the third as well as above it, but these intermediate boues 

 are more nearly equal in size, as in the Hog. Probably these specimens do not 

 belong to 0/-eofZo;i, isolated as they were; it remains for future discovery to deter- 

 mine the question positively. 



MERYCOCHCERUS. 



This genus belongs to the same family as Oreodon, and indeed is so closelj' related 

 to the latter that there would be no impropriety in regarding it as the same. The 

 number, relative position, form and constitution of the teeth are alike in both, though 

 the skull of the only known species upon which the name of Merycochcerus was 

 suggested, exhibits peculiarities which I have regarded as sufficient to characterize 

 tlie animal as belonging to a genus distinct from Oreodon. 



Merycochcerus proprius. 



This animal was larger than any of the described species of Oreodon, having ex- 

 ceeded 0. major more than a third, or it was about twice the size of 0. Culhertsoni. 

 Its remains, consisting of fragments of jaws with teeth, were obtained by Dr. Hayden 

 during Warren's Expedition of 1857, on the head-waters of the Niobrara River, oppo- 



