106 



ON THE EXTINCT MAMMALIA OF 



Okeodon. 





Measurements in 



lines. 







AFFINIS 



HVBKIDUS 



GUACILIS. 



Culbert'i. 



MAJOR. 



Breadth at post-orbital arches, .... 



36 



48 



26 



36 



48 



Breadth at ant-orbital margins, .... 



28 



36 



21 



27 



^^8 



Breadth at infra-orbital foramina, .... 



15} 



22 



12 



17 



21 



Breadth above last molars, ..... 



28 



38 



21 



30 



40 



Breadth of hard palate between first true molars, . 



lU 



17 



9 



15 



18 



Breadth of nasals above infra-orbital foramina, 



9 



lOJ 



8 



7i 



14J 



Breadth of nasals at ends of frontal processes, . 



' 101 



11 



8 



n 



14 



Length of nasals back of " " . . 



8 



10 



7 



lOa^ 



18 



Height of orbits, 



11 



16 



9 



15 



15 



Distance between supra-orbital foramina, 



6J 



8J 



5 



4 



7 



Length of upper true molar series, .... 



18 



22 



15 



22 



26 



Oreodon bullatus. 



The collection of fossils obtained in the Mauvaises Terres, in Dr. Hayden's expedi- 

 tion of the summer of 1866, has afforded me the opportunity of examining a multi- 

 tude of additional specimens of skulls and fragments of others, with teeth, of Oreodon 

 Culhertsoni. Besides those which present the ordinary individual variations, there is 

 one specimen which exhibits a most remarkable and unexpected deviation of charac- 

 ter. The specimen consists of a mature skull, much fractured, and having one side of 

 the face broken away. The other side retains the molars, with part of the corres- 

 ponding canine tooth. 



The skull agrees in general form, size and details of structure with that ordinarily 

 of Oreodon Culbertsoni, except that it possesses inflated auditory bullae proportionately 

 as large and nearly of the form of those of Oreodon major. In 0. Culhertsoni the 

 auditory bullge are proportionately less well developed than in 0. gracilis, so that I 

 was totally unprepared to see a skull, which otherwise would have been referred with- 

 out hesitation to 0. Cidhertsoni, with bullae approaching in size those of 0. major. 

 Had the cranium alone of this singular specimen been found, it would have been 

 viewed as pertaining to Agriochcerus, because in its form, size, construction, and 

 possession of large inflated auditory bullse, it agrees with that of the latter genus, but 

 then it has the face and teeth of Oreodon Oulhertsoni, The discovery of this specimen 

 throws doubt on a previous determination of some isolated crania which were referred 

 to Agriochoerus, and in part at an earlier period, or before an entire skull of the 

 latter had been obtained, to a supposed distinct genus named Eucrota;plius. 



Measurements of the above skull are given, in comparison with those of 0. Cul- 

 hertsoni, as specimen number 18, page 92. 



Of other portions of the Skeleton of Oreodon. 



The various collections of fossils from the Mauvaises Terres which I have had the 

 opportunity of examining, contain a great multitude of fragments of the skeleton of 



