176 THE SKULL. [chap. 



cartilaginous band, with one, or sometimes two, slender 

 ossifications near the middle part, representing the stylohyal. 



The skull of the Hippopotamus resembles that of the 

 Pig in many essential features, although its external form is 

 greatly modified. The brain cavity is very small, and the 

 face immensely developed. The orbits project outwards in 

 an almost tubular manner, and their margins are nearly, and 

 in some cases quite, complete posteriorly. The face is con- 

 tracted laterally in front of the orbits, and then expands 

 widely into a massive truncated muzzle, which supports the 

 great canine and upper incisor teeth. 



The anterior narial orifice is nearly circular; it is bounded 

 by the extremities of the narrow, but greatly elongated 

 nasals above, and laterally by the prominent, rounded, 

 rugged and massive premaxillge. At the anterior and lower 

 part of the orbit, the lachrymal is dilated into a great thin- 

 walled bony capsule, of such delicacy that it is nearly always 

 destroyed in the skeletons preserved in museums. This 

 opens into the nasal air-passages and has no connection 

 with the lachrymal apparatus. A similar but smaller dilata- 

 tion exists in many of the Pecora. 



The palate is long and narrow, and extends posteriorly a 

 short distance behind the last molar teeth. The internal 

 pterygoids end in well-marked stout hamular processes. The 

 glenoid surface of the squamosal is very much extended, 

 but not bounded externally by a projection from the malar, 

 as in the Pig, and the inner- half of its posterior margin is 

 produced into a tolerably well-marked postglenoid process. 

 The paroccipital process is long and conical, but far less 

 conspicuous than in the Pig. The tympanic bulla is pro- 

 portionately smaller, and of a trihedral form, ending in an 

 antero-inferior pointed process. Its interior is filled with 



