118 



On comparing the indices of the abnormal specimens with the 

 average normal indices it is seen that there are no very material 

 ditferences. What deviations there are in the main such as may be 

 met with in a series of naturally disposed teeth. The only striking 

 departures from the normal size are as follows. In No. I 64 is a 

 lower index for m^ (right) than any found in the normal mandibles; 

 and 73,07 for m^ (left) is higher than usual. In No. II 84 for m^ is 

 much, higher than obtained in the normal teeth. So, from both in- 

 spection and measurement, there is little difference between the six 

 usual teeth in the mandibles with more than the ordinary complement, 

 and the six corresponding teeth in more commonplace jaws. 



With regard to the supernumerary teeth, we may say that, with 

 the exception of m^ on the right side of No. I (where the index is 

 lower) they agree in a remarkable manner with the normal last tooth 

 in point of size. 



A question which suggests itself is whether there were any extra 

 teeth in the upper jaw in the two specimens. This is very difficult 

 to answer; but there are certain features which appear to otfer a 

 clue. It has been noted that the whole of the summit of m^ has been 

 subjected to wear. This may be the result either of unusually large 

 teeth in the upper jaw, or of some modification of their disposition. 

 From an examination of the transverse ridges and grooves one is led 

 to suspect that, either there was one more tooth than usual in the 

 upper jaw, or else that the m^ of the upper series was unusually large. 

 I incline to the former supposition. 



The question of whether supernumerary molars are more commonly 

 present in the upper or the lower jaw in Equidse can hardly be 

 satisfactorily answered from the data at our disposal; but it may 

 serve a good purpose to submit the eight recorded cases to analysis, 

 as follows : 



1) The figures in brackets refer to the list of references to litterature 

 at the end of this paper. 



