32 



THE ORIGIN OF VERTEBRATES 



earliest fishes and members of the Palaaostraca, the dominant race of 

 arthropods which swarmed in the sea at the time : a similarity which 

 could never have been suspected by any amount of investigation 



Fig. 16. — Bothriolepis. (After Patten.) 

 An., position of anus. 



among living forms, but is immediately revealed when the ages 

 themselves are questioned. 



I have not reproduced any of the attempted restorations of these 

 old forms, as usually given in the text-books, because all such restora- 

 tions possess a large element of fancy, due to the personal bias of the 

 observer. I have put in Eohon's idea of the general shape of Tre- 

 mataspis (Fig. 17) in order to draw attention to the lamprey-like 

 appearance of the fish according to his researches (cf. Fig. 18). 



Fig. 17. — Kestoration of Tremataspis. (After Kohon, slightly modified.) 



*&s( 



Fig. 18. — Ammoecetes. 



The argument, then, from geology, like that from comparative 

 anatomy and from the consideration of the importance of the central 

 nervous system in the upward development of the animal race, not 

 only points directly to the arthropod group as the ancestor of the 



