THE TEETH. 173 



sense, much too subordinate a part of the body to justify so 

 great a weight being attached to their structure in so im- 

 portant a question. There are, however, good reasons for 

 this prominent consideration of the structure of the teeth ; 

 and it is with perfect correctness and propriety that sys- 

 tematic zoologists have, for more than a century, given 

 special weight to this character in systematically dis- 

 tino-uishinor and arrano-inof the mammalian orders. The 

 number, form, and disposition of the teeth are transmitted 

 much more accurately within the respective orders of the 

 mammals than are most other zoological characteristics. 

 The structure of the human teeth is well known. In matu- 

 rity there are 32 teeth in our jaws, and of these 82 teeth, 

 8 are front-teeth, 4 canme-teeth, and 20 molar-teeth. The 

 eight front-teeth or incisors (denies incisivi), which are 

 situated in the centre of the jaws, exhibit characteristic 

 differences in the upper and lower jaw. In the upper the 

 inner incisors are larger than the outer; in the lower jaw, 

 on the contrary, the inner incisors are smaller than the 

 outer. Next to these, on each side, both in the upper and 

 lower jaw, is a corner- tooth, which is larger than the in- 

 cisors, the so-called eye-tooth, or canine (dens cavdnus). 

 Sometimes this tooth becomes very prominent in Men, as in 

 most Apes and many other Mammals, and forms a sort of 

 tusk. Finally, next to this, on each side, and in each jaw, 

 are situated five back-teeth, or molar-teeth (denies molares)^ 

 of which the two foremost (the bicuspid teeth) are small, 

 have but a single fang, and are subject to the change of 

 teeth, while the three hinder molars are much larger, have 

 two fangs, and do not appear till after the temporary teeth 

 ha VG been shed (so-called " grinders "). The Apes of the 



