12 THE ART OF MORPHOLOGY 



thing else besides. All homoplasy is convergence, 

 but all convergence is not homoplasy ; and the 

 same dictum may be repeated, mutatis mutandis, 

 for cenogenesis. 



Professor H. F. Osborn, in the paper to which 

 I have referred in the Preface, finds homoplasy 

 to be of very great importance in the evolution 

 of mammalian teeth, "because it seems to coin- 

 cide with the principle of definite or determinate 

 evolution" which has proceeded "independently 

 in a great many different families of mammals." 

 He discusses the special value of the evolution 

 of teeth as bearing upon homoplastic mutations, 

 inasmuch as teeth are preformed beneath the 

 gum so that "new cusps, folds, crests, and styles 

 are invariably congenital." 



