130 PROF. DR. L. BOLK 



learned author cannot decide as to the origin of this extra tooth 

 standing outside the arch. He hesitates between the possibihty 

 that the extra tooth originated by a division of M2 and the 

 possibility that it represents an addition to the normal series. 

 I believe the third possibihty, i.e., that this supernumerary ele- 

 ment represents the hindmost element of the outer row of teeth 

 (a third paramolar), is much more evident. 



Returning again to the scheme given in figure 21a final remark 

 may be made concerning the lost third premolar of man. As 

 shown clearly by the given scheme, this tooth alternates with 

 the M] and Pai of the outer row. The reappearance of this 

 tooth as an atavistic variation in man is a very rare event. 

 However, it seems to me that this tooth causes an anomaly 

 occurring frequently in the lower first molar of man. H. is pointed 

 out in the second section, that in the lower jaw the para- 

 molars, in case of coalescence with the second or third molars 

 often appear as a supernumerary root at the anterior buccal 

 corner of the molar, contrary to the upper molars in which the 

 paramolars most frequently are found as an additional tubercle 

 coalesced with the anterior buccal cusp of the molar. Now in 

 the first lower molar a corresponding pecularity, such as that in 

 the second and third, occurs occasionally. In this tooth also an 

 additional root sometimes is present, however, not at the outer 

 side as in the second and third molars, but at the distal corner of 

 the inner side, i.e., lingually from the distal root. Perhaps this 

 warrants the supposition that this additional root is not an extra 

 root at all, but simply the result of a division of the normal pos- 

 terior root. This supposition is, however, an erroneous one. 

 Out of 1800 first lower molars of man I have collected eighteen 

 instances of a supernumerary posterior root as described, and a 

 comparison of these specimens proves that there is no question 

 about any division of the posterior root. For if such really was 

 the case, undoubtedly the collected specimens must show the 

 supposed division in different degrees of perfection, beginning 

 with a simple bifurcation of the apex of the root and continuing 

 until a complete reduplication appears, as seen in other cases 

 of the division of roots of teeth. But there is not the least indi- 



