SPECULATIVE ZOOLOGY. 



371 



paleontological record is faulty through incompleteness, that of em- 

 bryology is faulty through distortion and secondary modification. In 

 general we do find the young stages of related species more like each 

 other than the adults, and the distinctive characteristics of each are 

 usually acquired gradually during the process of development ; but 

 this rule is by no means universal, and there are very many cases in 



Fig. 6. 



Fig. 5. 



which the adults of related species are more alike than the young, and 

 in some cases the difference between the young forms is so great that 

 their close relationship would hardly be suspected until each had been 



