neio Type of Reptilian Tooth. 



291 



smallest and scarcely affects the pulp-cavitj, but the otlier 

 four are deeper than wide; B and G on the external border 

 are narrower than D and E on the internal border. All are 

 to be described as canals which are open externally. They 

 are fewer and larger than tlie ffrooves on the roots o£ teeth 



Fk. 1. 



Outline of the proximal surface, sliowing the five bars of tho tooth (1-5) 

 and inward folds (A-E) which divide up the pulp-cavity. 



of some species of Ichthyosaurus, and rather suggest the 

 folded condition of the teeth in genera of mammals wiiich 

 approximate to South-Africiin reptiles in parts of their 

 skeletons. 



Transverse section in the middle of the specimen, showing the 

 dimiDishiug pulp-cavity. 



To determine the structure of the tooth more exactly it was 

 divided transversely in the middle of its short length. The 



