THE ANIMAL KINGDOM. 



the teeth implanted in the premaxillary bones, which are always of a com- 

 paratively simple type, with single roots, are termed incisors. In the great 



Fig. 3. UPPER JAW OF THE GORILLA. 

 majority of Mammals, there are 



Fig. 5. PALATE OF THE GORILLA. 

 In the palate the three hindmo-t teeth 

 are the molars, in advance of which are 

 the two premolars ; the si::gle large tooth 

 on each side is the tusk, or canine, in front 

 of which are the two pairs of incisors. 



Fig. 4. LOWER JAW OF THE GORILLA. 



not more than three pairs of these teeth, 

 although there may be four or five pairs in 

 the Pouched Mammals. The first tooth 

 in the upper jaw, which is implanted in 

 the maxillary bone, and is very generally 

 long and tusk-like, is termed the canine ; 

 this tooth being also of simple type, and 

 generally with a single undivided root. 

 Behind this come a series of, at most, four 

 pairs of cheek-teeth, which have gener- 

 ally, except the first, two roots each, and, 

 in ordinary Placental Mammals, are pre- 

 ceded (as are the incisors and canine) by 

 milk-teeth in the young. To these teeth, 

 which may be reduced to a single pair, is 

 applied the term, premolars. Behind 

 these come the true molars, which have 

 generally broad complex crowns and 

 branching roots, and are not preceded by 

 milk-teeth. In Placental Mammals there 

 are but seldom more than three pairs of 

 molars, but in Marsupials the ordinary 

 number is four. In the lower jaw the 

 tooth biting in front of the upper canine 

 is the lower canine, in front of which are 

 the incisors. In. the Placental Mammals 

 these do not exceed three pairs, and are 



