292 Messrs Duckworth & Fraser, A Description of 



A Description of some dental Rudiments in human crania. 

 By W. L. H. Duckworth, M.A., Jesus College, and D. H. Fraser, 

 Cams College. 



[Read 19 February 1900.] 



In this communication it is desired to draw attention to the 

 occurrence in human crania of small discrete dental masses which 

 appear with great, though not with absolute, constancy, on that 

 portion of the alveolar margin of the upper maxilla which lies 

 between the last premolar and the first molar teeth. These 

 occurrences appear to us to raise some questions of interest which 

 may be stated in the following order : 



(i) the nature of these rudiments ; which may conceivably be 



(a) remnants of teeth of the milk or temporary den- 



tition which have not been completely displaced 

 and ejected by their permanent successors, or 



(b) aborted or vestigial premolars which would correspond 



to the 3rd premolars of the platyrrhine apes, or 



(c) elements bearing no homological relation to those 



of either of the two normal sets (temporary and 

 permanent) of the primate dentition ; 



(ii) the frequency with which these rudiments appear : herein 

 considering the possible influences of 



(a) Race, 



(6) Age, 



(c) Sex ; 



and (iii) the bearing on the preceding questions, of observations 

 made on other primates and mammals than man, but 

 especially on the anthropoid apes. 



The general position of these rudiments has already been 

 indicated, and the results of our observations on this point are 

 embodied in a Table of Classification. It is necessary to note 

 that this is not a common situation for the occurrence of ordinary 

 supernumerary teeth, by which we mean teeth that resemble in 

 size those immediately adjacent to them : such teeth are of most 

 frequent occurrence in the neighbourhood of the incisors (see 

 Fig. 1 : mandible of an aboriginal Australian with a supernumerary 

 incisor) and of the molars (see Fig. 2, for the occurrence of a 

 4th molar tooth in the mandible of an Orang-utan). Secondly, 



