XL] PROBOSCIDEA. 183 



The lachrymal is small, placed almost entirely within 

 the margin of the orbit, and ends anteriorly in a projecting 

 antorbital process. The zygomatic arch is slender and 

 straight, the malar being small, and forming only the middle 

 part of the arch, the anterior portion of which is (unlike 

 that of all Ungulates) formed by the maxilla. 



The elongated, tubular nasal cavity forms a sigmoid 

 curve, being directed (from below) at first forwards, then 

 upwards, then forwards. The olfactory chamber is a 

 comparatively small fossa in the middle third of its posterior 

 wall, filled by the complex ethmoturbinals. The maxillo- 

 turbinals are but rudimentary, the narial passage being quite 

 free.^ The floor of the palate is completed posteriorly by 

 well-developed palatines {PI). The pterygoid (/Y) is slender 

 and very early ankylosed with the pterygoid process of the 

 alisphenoid, which is greatly expanded, and hollowed in 

 front, being spread round the dilated posterior margin of 

 the alveolar portion of the maxilla, and aiding to close the 

 great alveolar cavity of the hindermost molar tooth. 



The squamosal {Sq) forms a considerable part of the cranial 

 wall, extending outside the small alisphenoid to meet the 

 frontal, and externally sends off a broad post-tympanic pro- 

 cess, which meeting (though not uniting with) the hinder bor- 

 der of the glenoid fossa in front, bounds the bony external 

 auditory meatus, to which the tympanic contributes very 

 little. The latter bone is, in the young specimen, completely 

 united with the periotic, but not with the squamosal. In- 

 feriorly it forms a large, rounded, but not very prominent 

 auditory bulla, deeply notched on its inner side by the 

 canal for the internal carotid artery {c c). , The periotic 

 {Per) presents a large surface within the cranium without 



^ The elongated proboscis probably supplies their place functionally 

 in warming the inspired air. 



