PREFACE 



THE older odontography or description of teeth treated each type as 

 a distinct and perfect form in itself. Curler's Odontographie '/<--. 

 Mammiferes, (licliel's Odontographie, Owen's Odontography are examples 

 of more or less comprehensive treatises in the pre-evolutionary spirit. 

 They antedate the discovery of what may be called the ' new odonto- 

 graphy,' which is based upon the unity of dental type, upon the 

 evolution of the teeth of mammals from a common reptilian prototype, 

 and which treats of each form in relation to its origin, its descent, its 

 gradual complication, and the laws of analogous evolution or independent 

 production of similar forms. 



The new odontography centres around the ' tritubercular theory ' of 

 Cope. This theory had wider acceptance ten years ago than it has 

 to-day : there has been a strong reaction against certain features of it on 

 the part of many of the most able anatomists. This is partly due to 

 misunderstanding, partly to the fact that all the evidence has never 

 been fully marshalled, partly to the discovery of new embryi (logical 

 and palaeontological evidence which may disprove certain features of 

 the theory : but chiefly to the fact that some of the most decisive 

 and convincing palseontological evidence in support of the theory has 

 not been clearly advanced. It is hoped that this collection of the 

 contributions of the writer, with additional observations, illustrations, 

 and data, and with a discussion of various other theories and criticisms 

 will serve to convince the reader and student that the new odonto- 

 graphy in its general principles rests upon an adequate basis of evidence 

 and, while subject to modification in many details, marks a turning 

 point in the science of the teeth. 



