416 THE EVOLUTION OF MAN. 



Johannes Muller referred the Lancelet to the class ol 

 Fishes, though he insisted that the differences between this 

 lowest of the Vertebrates and the lowest Fishes are much 

 more considerable than the difference between all Fishes and 

 the Amphibia. But this is far from expressing the real 

 significance of this important little animal. Indeed, we 

 might confidently lay down the proposition that the dif- 

 ference between the Amphioxus and the Fishes is far greater 

 than between the Fishes and Man and all other Yertebrates. 

 Nay, so widely does the Amphioxus differ in its whole 

 organization from the rest of the Vertebrates, that, according 

 to the laws of systematic logic, we are forced to distinguish 

 two main divisions of the vertebrate tribe: (1) the Skull -less 

 Animals, or Acrania (the Amphioxus and the extinct allied 

 forms) ; and (2) the Skulled Animals, or Craniota (Man and 

 all other Vertebrates.) 115 



The first and lower division consists of Vertebrates 

 without head, brain, or skull, for which reason they are 

 called Skull-less Animals, or Acrania. Of these, the only 

 extant representative is the Amphioxus, though in the 

 earlier periods of the earth's history very numerous and 

 varied forms belonging to this division must have existed. 

 We may here lay down a universal law, which must be 

 accepted by every adherent of the theory of evolution : viz., 

 Buch entirely peculiar and isolated animal forms, as the 

 Amphioxus — which apparently stands alone in the whole 

 system of animals — are always the last survivors of an 

 extinct group, numerous and diversified forms of which 

 existed at an earlier period. As the whole Amphioxus is 

 soft, and has no firm organs, capable of being fossilized, we 

 may suppose that all its numerous extinct kindred were 



