MAMMALIA. 525 



Keeping these points in mind, we may glance at the 

 anatomy of the two types. 



Placing the two skulls before us, we note their features 

 in common as follows : — In each the incisor teeth are 

 small and pointed and are never more than f, a distinc- 

 tion from Polypf'otodontia ; the canines are long, powerful 

 and pointed ; and the premolars and molars have sharp- 

 edged cusps, with an absence of the flat grinding surfaces 

 seen in the herbivorous types. In both there is a specially 

 large cusped tooth in upper and lower jaw which is called 

 the ''carnassial "-tooth, usually said to be used for breaking 

 slippery bones. The glenoid cavity of the squamosal is a 



Fig. 362. — Lateral View of Lion's Skull x \. {Ad nat.) 



I Zygomatic Arch. ^^ Auditory Bulla. 



Carnassial Tooth. Postglenoid Process. 



transverse groove, and into this there fits the cylindrical 

 condyle of the mandible. Owing to this arrangement the 

 mandible can only move in a perpendicular plane. Imme- 

 diately behind the glenoid cavity is a wide process of the 

 squamosal, called the postglenoid process, which prevents 

 all backward horizontal motion of the mandible. 



On the cranial surface there are at least two large bony 

 crests — the sagittal crest along the middle dorsal line and 

 the occipital crest from side to side at the junction of 

 parietals and occipitals. These form the surfaces of origin 

 for the large jaw-muscles {temporalis) which pass down in 



