neio Ti/pe of Reptilian Tooth. 



291 



Braallest and scarcely afficts the pulp-cavity, but the other 

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

 are narrower than D an I E on the internal border. All are 

 to be described as canals which are op3n externally. They 

 are fewer and larger than the grooves on the roots of teeth 



Outline of the proximal surface, showinj? the five bars of thi tooth (l-o) 

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



of some species of Ichthyosaurus, and rather suggest the 



folded condition of the teeth in genera of mammals which 



approximate to South-African reptiles in parts of their 

 skeletons. 



TransTerse section in tlio middle of the specimen, showing the 

 dimiiiishiujj pulp-cavity. 



To determine the structure of the tooth more exactly it was 

 divided transversely in the middle of its short leiif^th. The 



