ably backward on outer side. Main axis of shafts diverging 

 posteriorly, the angle at which they are set such that a con- 

 spicuous sub- apical notch is formed on outer side of cutting edge of 

 tooth immediately behind margin of enamel. First upper molar 

 three-rooted, the anterior root largest, projecting conspicuously 

 forward beyond base of crown, separated from more posterior 

 roots by an appreciable space ; crown decidedly longer than 

 that of in 2 and m 3 together, its area nearly 1£ times as 

 great ; anterior border of crown smooth or with a slight angle 

 representing cingulum ; first lamina with crescentic form much 

 distorted by the displacement backward of 21 to a position 

 essentially in line with 25 and 26 ; 23 well developed, nearly 

 equal to 24 or 26, but not so large as 21 , its separation from 22 

 marked by an evident re-entrant extending almost to base of 

 crown ; 21 separated from (2 by a broad, flattened or slightly 

 concave area which imparts to the antero-internal border of the 



crown a characteristic obliquely-trun- 

 cate appearance ; second lamina more 

 regularly crescentic than first, but 

 with evident traces of the same dis- 

 tortion ; third lamina represented by 

 well developed 28 and 29 essentially 

 similar to 25 and 26, but with no 

 trace of tl unless a short enamel 

 ridge connecting 24 and 28 be inter- 

 preted as representing a trace of this 

 tubercle. Second upper molar with 

 first lamina represented by a well 

 developed, sub-terete 21 about as large 

 as the outer tubercles of m l ; second 

 lamina with 24 slightly larger than 

 26 and connected posteriorly with 

 28 as in the preceding tooth ; third lamina about as in to 1 , 

 but 29 reduced, decidedly smaller than 26, though marked 

 off from 28 by an evident re-entrant angle. Third upper 

 molar relatively smaller than in any of the other European 

 Muridse, its area scarcely greater than that of terminal heel of 

 m 2 . In form the crown is sub-circular with a small, often 

 indistinct tubercular antero-internal supplement representing 21. 

 Anterior lower molar with crown about as long as those of the 

 two succeeding teeth together, its area about equal to them ; 

 first lamina reduced to a single large tubercle forming the entire 

 anterior border of the tooth and situated slightly internal to the 

 median line of the crown ; internally it is separated from second 

 lamina by a deep re-entrant depression, but externally it is 

 connected with outer tubercle of second lamina by a high, some- 

 times distinctly tubercular ridge, which occasionally * forms a 



Fia. 178. 

 Mils mmculus. Cheek-teeth. 

 (Antero-external re-entrant angle 

 of mj usually much less evident.) 



X10. 



As in specimen represented in fig. 178. 



