384 Annals of the South African Miiseum. 



The teeth described and figured by Thomas in the upper jaw are 

 apparently do, dp', dp^, dp3, dp4, dp5, and dp^. In his specimen, as 

 in mine, it is dp4 and dp^ which are best developed. The little tooth 

 which he observed on one side of one of the specimens near the 

 premaxillo-maxillary suture is evidently di3. The four milk teeth 

 he found in the lower jaw clearly correspond to the teeth I call dp3, 

 dpt, dp5, and dp"^. 



The full dentition of Orycterojms may be represented diagram- 

 matically as follows : — 



Molars. 



1 2 3 



1 2 3 



"While the discovery of this full set of milk teeth, including distinct 

 incisors, confirms the opinion that has been growing of late years 

 that Orycterojnis is not a true Edentate, it does not by any means 

 definitely decide for us where else it ought to be placed. 



Thomas, after showing reason for removing it from the Edentata, 

 adds : " But if Oryctcropus is not genetically a near relation of the 

 Edentata, we are wholly in the dark as to what other Mammals it is 

 allied to." Kitchen Parker, from the examination of the developing 

 skull, was specially impressed by its apparent affinities with Marsu- 

 pials and the lower Insectivores. Elliot Smith, in his recent memoir 

 on " The Brain of the Edentata," says: " The features of the brain 

 conclusively show that Orycterojnis is no more nearly related to the 

 American forms [Edentates] than the Sheep is to the Dog." He 

 points out a number of resemblances of the brain to that of the Pig 

 and Musk deer, and thinks " in all probability Oryctcropus became 

 specialised from the generalised type at about the same time as 

 the Ungulata," and that it may be a branch from the Subungulate 

 stem. 



While fully aware of the fact that many mammals have the 

 number of molars largely in excess of that found in their ancestors, 

 I feel inclined to think that there is some phylogenetic reason for 

 Orycterojnis having a definite number, and that its ancestor had 

 a dental formula of * f c \ m f . The evidence of six premolars would 

 seem to remove it from any close relationship with other living 

 forms, and to suggest the possibility of its being related to some 

 of the Mesozoic mammals, a number of which have probably an 

 identical dental formula. 



