HOMOLOGIES OF THE HUMAN TEETH. 811 



set of teeth is in place, its nature is indicated by the 



r T .3—3 1—1 4—4 3—3 ., Ti . 



lormula: — i , c ,v , m =44: wnicn sia;- 



3—3' 1—1'^ 4— 4' 3—3 ^ 



nifies that there are, on each side of both upper and lower 



jaws, three incisors, one canine, four premolars, and three 



molars, making in all forty-four teeth ; each distinguished 



by the symbol marked in the cut. 



When the premolars and the molars are below their 

 typical number, the absent teeth are missing from the fore 

 part of the premolar series, and from the back part of the 

 molar series. The most constant teeth are the fourth 

 premolar and the first true molar ; and, these being known 

 by their order and mode of development, the homologies 

 of the remaining molars and premolars are determined by 

 counting the molars from before backwards, e. g., " one," 

 " two," " three," and the premolars from behind forwards, 

 "four," "three," "two," "one." 



Examples of the typical dentition are exceptions in 

 the actual creation ; but it was the rule in the forms of 

 mammalia first introduced into this planet; and that, too, 

 whether the teeth were modified for animal or vegetable 

 food. 



With regard to the human dentition, the discovery by 

 the great poet Goethe of the limits of the premaxillary 

 bone in man, leads to the determination of the incisors, 

 which are reduced to two on each side of both jaws ; the 

 contiguous tooth shows by its shape, as well as position, 

 that it is the canine, and the characters of size and shape 

 have also served to divide the remaining five teeth in 

 each lateral series into two bicuspids and three molars. 

 In this instance, the secondary characters conform with 

 the essential ones. But, since we have seen of how little 

 value shape or size are, in the order carnivora, in the de- 



