54 



OREODON. 



The specimen corresponds in its proportions and details with specimen 2. (Plate 

 VI. upper part of Fig. 4.) 



From the collection of Dr. Owen. 



MEASUREMENTS. 



Inches. Lines. 



Length of series of upper molars 2 1 



Breadth of face at infra-orbitar foramina ....... Hi 



Distance between supra-orbitar foramina ....... 4 



Distance between frontal angular processes ....... 8 J 



4. The skull accompanied by the right side of the lower jaw of a young animal. 

 The former has the posterior and superior portions of the cranium and the nose 

 broken away; the latter the ramus and symphysis. 



The upper jaw contains on the left side the molar series nearly complete, con- 

 sisting of the first permanent premolar, the temporary molars, and the succeeding 

 two permanent true molars which are fully protruded. 



The portion of lower jaw contains two temporary molars, and the succeeding 

 two permanent molars. 



The forehead of this specimen is remarkable for its flatness ; being much more 

 arched in the adult. (Plate V. Figs. 3, 4 ; VI. Figs. 6, 7.) 



From the collection of Dr. Owen. 



Average Measurements of Specimens of Oreodon gracilis. 



Estimated length from summit of inion to incisive alveoli 



Breadth below the orbit at the maxillo-malar suture 



Breadth of cranium at most prominent portion of temporal fossas 



Breadth of cranium at narrowest portion .... 



Estimated length of sagittal crest ..... 



Length of forehead in median line ..... 



Breadth of forehead at middle of post-orbital arches 



Breadth of face from above the lachrymal tubercle 



Breadth of face at infra-orbitar foramina .... 



Breadth of face between ends of frontal angular processes 



Height from middle palate suture to fronto-nasal 



Height from middle palate suture on a line with the first premolar 



Diameter of the orbit .... 



Breadth of palate between fourth premolars 



Depth of lower jaw at last molar 



Depth of lower jaw at third premolar 



Length of series of upper molars 



Length of series of lower molars 



Length of series of upper true molars 



Length of series of lower true molars 



Antero-posterior diameter of upper middle true molar 



Autero-posterior diameter of upper fourth premolar 



Antero-posterior diameter of last lower molar 



Antero-posterior diameter of second lower true molar 



Antero-posterior diameter of third lower premolar 



Inches. 



Line 



4 



8 



o 



5 



1 



4i 





lOi 



1 



10 



1 



7 



8i 



J 

 9 



o 



1 



2 



u 



1 



2i 



1 



4 





5 





3 





7i 





5J 



