418 ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



of which the malar, temporal, and the maxillary bones concur almost 

 equally. 



The maxillary bone advances under the orbit, and forms a floor 

 there : it has no apophysis, either frontal or malar, to join the zygo- 

 matic arch to the frontal, and to close the orbit behind. 



The suborbital foramen is small, more high than broad, and near 

 the bottom of the nasal fissure above the first molar tooth. The subor- 

 bital canal is long and narrow ; it opens behind above the fifth molar 

 tooth. 



The maxillaiy bones form in front a projecting apophysis parallel 

 to the nasal bones, and situated under them, which articulates with 

 the incisors. The alveoli of the incisors form together an angle of 

 more than eighty degrees. The foramen incisivum is very large, 

 elliptical, and not divided into two; one half of its length is in the 

 maxillary bones. 



The incisive bones are directed to the extremity of the anterior 

 apophysis of the maxillary bones, with an ascending or palatine apo- 

 physis. At their upper edge is a small apophysis in the form of a 

 square plate, which rises towards the roof formed by the nasal bones, 

 and which should be remarked so much the more carefully, as it con- 

 stitutes one of the characters of this species. 



The nasal bones have a size and thickness, of which there is no in- 

 stance in the other quadrupeds ; they form a vault, which slopes over 

 the incisive bones, and carries the horn. In our animal, their upper 

 surface is like a head of cauliflower. 



Between them and the incisive bones, as also the part of the maxil- 

 lary bones which carry the latter, is that great nasal fissure which cha- 

 racterises, at the first glance, the cranium of the rhinoceros. The 

 consequence of the depth of this fissure is, that in this animal three 

 pairs of bones, the nasal, incisive, and maxillaiy bones, contribute to 

 form the contour of the external openings of the nares, whilst in other 

 quadrupeds it is only the two first that do so, except the tapir. 



The vomer is ossified only in its most posterior part, and there re- 

 mains nothing in the four-fifths of its length, even in our perfectly adult 

 rhinoceros, and where all the sutures were effaced. This remark is 

 essential for comparing living with fossil rhinoceroses. 



The posterior fissure of the palate is very deep, for it advances to 

 nearly opposite the fifth molar tooth. The suture which separates the 

 palate bones from the maxillary bones corresponds to the interval be- 

 tween the fourth and fifth molar tooth. 



The pterygoid processes are short in the longitudinal direction, but 

 very high in the vertical, simple and only a little forked towards the 

 end. 



The middle part of the sphenoid bone is narrow, and goes much 

 more posteriorly than its pterygoid wings ; its articulation with the 

 basilar part of the occipital bone forms a very perceptible projection. 

 Along the middle of this basilar part is a projecting ridge, which widens 

 and flattens towards the lower edge of the occipital foramen. 



The rocher is small and very irregular ; the foramen lacerum is large, 

 and extends the entire length of the inner edge of the rocher. The gle- 



