THE TEETH OF IN SECT IVOR A. 



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furnished with four cusps, of which the antero-extcrnal one 

 is far the longest and sharpest. 



The first upper true molar has a square crown, upon 

 which are four sharp cusps : it is implanted by four roots. 



FIG. 174('). 



The second true molar is also square, quadricuspid, and 

 has four roots ; but it is much smaller than the first, while 

 the third upper true molar is quite a small, compressed, 

 double-rooted tooth, with a thin-edged crown. 



In the lower jaw the first incisors, less widely separated 

 than the upper, are also the largest ; then follows another 

 tooth termed incisor, on account of its relation to the upper 

 incisors when the mouth is closed. The third tooth is 

 much larger, and of peculiar form. The fourth tooth from 

 the front is a small single tooth, like the third, but upon a 

 smaller scale. Next behind it, comes a tooth which is very 

 much larger, and its crown carries two principal cusps with 

 a small subsidiary cusp. The next tooth (first true molar) 

 has an oblong crown beset with five sharp cusps, of which 

 four are arranged at the corners of a square, while the fifth, 

 obviously an elevation of the cingulum, lies a little in front 

 and towards the inside of the tooth. In the second true 

 molar the fifth cusp is but little indicated, while the last 



0) Upper and lower teeth of the Hedgehog. 



