MAMMALIA, 527 
The skull of the dog has a dental formula of $342, and 
it has thus two molars (one on each side) short of the full 
typical Eutherian dentition. In this and in many other 
respects the dog is the more generalised type of the two 
(ff. diet). 
The cat has a dentition of 3131, hence there has been 
a great reduction in the number of teeth, especially as the 
upper molar is also merely a vestige. In this case, however, 
as in the dog, the last premolar of the upper jaw and first 
Fi 
ee 
g. 364.—VENTRAL VIEW OF LIOoN’s SKULL x ¥. 
Note the large round tympanic bulla, the wide zygomatic arch, the shortened 
facial region and small number of cheek-teeth. Dental formula—3.1.3.1. 
molar of the lower jaw are the carnassial, hence it is easy to 
observe which teeth have disappeared. Correlated with the 
reduction in number of the teeth is the shortening up of the 
jaws, involving a still further reduction of the facial region. 
If the mandible be regarded as a lever (of the third order), 
the “‘ weight” will act at the level of the canines, the fulcrum 
is at the glenoid cavity and the ‘‘ power” at the insertion of 
the jaw-muscles, a little in front of the glenoid cavity. 
Hence the simplest way of increasing the “power” is to 
move the “weight” nearer the “fulcrum,” or, in other 
