14 Firerp Museum or Natura History — Zooroey, VoL. XI. 
lary bone just behind the premaxillary suture, or what might 
be described as at the angle of the front of the jaw, one on each 
side. 
Premolars: Teeth on side of jaw (maxillary bone), between the 
canines and the molars. These teeth replace the milk teeth at 
an early age. 
Molars: The “back teeth,” situated immediately behind the pre- 
molars on side of jaw. These are permanent teeth which are 
not represented early in life by milk teeth. 
Skull of a Carnivore. Skull of a Rodent. 
(Canines present.) (Canines absent.) 
n, Incisor teeth or incisors; 0, canine teeth; p, premolar teeth; r, molar teeth; s, upper carnassial 
tooth; t, lower carnassial tooth. 
Certain forms of teeth are given special names. In carnivorous 
mammals, for example, the anterior molar in the lower jaw and the 
posterior premolar in the upper are larger and more prominent than 
the others and are known as the carnassial (or sectorial) teeth. Those 
with flattened crowns, from which points or tubercles arise, are called 
tuberculate teeth, etc. In the Insectivora many of the teeth are of a 
generalized type, being small, single pointed and showing little or no 
difference in shape and are known collectively as unicuspid teeth. 
Further remarks on this subject are unnecessary here, as the more 
important dental characters are treated under the different families 
and genera. 
For convenience in describing the dentition the following formula 
has been adopted by zodlogists:— 
I. =incisors, C. =canines, Pm. =premolars, M. = molars. 
ae dental formula of the Virginia Opossum would, therefore, read as 
ollows: 
I, 523, uals 373 a ee 
+ “q-1 . 3-3 M. 414 5°, 
the numbers above the line indicating the number of teeth on the 
upper jaw, and those below the line, on the lower, 
