26 



E. M. MUSEUM MEMOIRS. 



Comparative Measurements of Skulls. 



Lox. Uinta. 



M. M. 



Head, length over all, (Lox. y]\ inches), estimated for Uintatherium 91 .76 



Head, breadth of, above orbits 195 .22 



Bony palate, length 34 .22 



Nasal bones, length 53 .35 



Snout, breadth 165 .12 



Median protuberances, distance between, at summits yj .33 



Distance between median and posterior protuberances 45 .37 



Distance between anterior protuberances and nasal tips 35 .25 



Width between zygomatic arches 32 .30 



Distance from angle of nares to tips of premaxillaries 12 .114 



Distance from angle of nares to tips of nasals 18 ,162 



Anterior protuberance, height from base 16 .175 



Posterior protuberance, height from supra-cerebral fossa 25 .27 



Occipital crest at broadest point 28 



Occipital crest, height from base of skull 31 



Comparison with Proboscidian Skull. Some of the points which are sug- 

 gested by a comparison of the skull of Loxolophodon with that of the elephant 

 are of considerable value as showing the common origin of the two forms. 

 Others point to a wide divergence and perhaps predominate over those indicat- 

 ing an approximation of structure. These may be placed with the comparisons 

 of the same character which are inserted with the description of the skeleton 

 which follows, before conjecture can be made as to the degree of divergence. 

 The features of agreement are: (i) Both possess an aUsphenoid canaU (2) 

 The anterior portion of the zygomatic arch is made up by the maxillaries ; (3) 

 The frontals are narrow and do not join the premaxillaries ; (4) There are 

 extensive air-cavities in the skull. In the following respects the Dinocerata 

 differ from the Proboscidia: (i) The periotic bones have a considerable exposure 

 at the side of the skull ; (2) There is a condylar foramen ; (3) There are post- 

 glenoid processes ; (4) There are no postorbital processes ; (5) There are no 

 upper incisors. 



Comparison with Rhinocerus. The skulls of the Dinocerata agree with those 

 of the Rhinocerotid(Z in the following particulars : (i) They have no postor- 

 bital processes ; (2) They possess an alisphenoid canal ; (3) The nasals are 

 produced forwards. The points of disagreement in the Rhinocerotidce are : 

 (i) The maxillaries, as in all ungulates, form a small portion only of the zygo- 

 matic arch ; (2) The external auditory meatus has a more posterior position ; 

 (3) The mastoid portion of the temporal bone is not exposed. 



