490 CLASSIFICATION. 



Such questions cannot receive at present any satis- 

 factory answer, but the evidence we have seems to 

 indicate that pre-existing forms were simpler, and less 

 specialised in structure than those now existing, and 

 hence if we meet with malformations of a simple kind, 

 we may consider them as possible reversions ; while, if 

 they present features of increased complexity, and 

 more sharply defined differentiation, we may assume 

 them to be evidences of a progressive rather than of a 

 retrogressive tendency. 



That monstrosities so called may become the starting 

 points of new forms is proved by the circumstance that, 

 in many cases, the peculiarities are inherited so that a 

 new " race " is produced and perpetuated : and if a 

 new race, why not a new species ? The difference is 

 one of degree only. 



