OUR FACE FROM FISH TO MAN 



Fish-Traps and Faces 



THE FIRST MOUTHS 



From air-breathing fish to man the general 

 course of evokition seems clear enough, at least in 

 its broad outlines. But when we inquire whence 



'Sexglanas 



spinalcord notochord 



ffi&sUtsl mouih 

 Ciliated^rooire 



Fig. 54. Anatomy of the Lancelet, the Most Primitive Living 

 Chordate Animal (after Delage and H^rouard). 



A. Entire animal, seen as a semi-transparent object; B. Longitudinal 

 section. For details, see p. xxiv. 



came the fish, the evidence while extensive is 



somewhat ambiguous and there is room for sharp 



differences of opinion. On the one hand, there is 



Professor Patten, who derives the whole vertebrate 



series from very ancient jointed animals remotely 



allied to the modern scorpions and Limulus; on 



the other hand, there are the more orthodox 



92 



