OUR ANCIENT RELATIVES 



ing or pushing the food within its reach, these 

 mouth-legs finally culminating in the various and 

 highly refined burglar tools so well wielded by the 

 swarming hosts of insects. 



According to Professor Patten of Dartmouth, 

 the vertebrates were derived from the arachnid 

 stem — an ancient branch of the jointed animals 

 (arthropods) , that is represented today by Limulus, 

 the "king-crab" (which is not a crab at all), and 

 by the arachnids (scorpions and spiders). But if 

 these disagreeable creatures are our remote rela- 

 tives, then the highly developed head which they 

 had acquired after so many millions of years of 

 struggle all had to be largely made over when the 

 vertebrate stage of organization was reached. 

 They had to sacrifice their elaborate leg-jaw 

 apparatus, their very mouths were stopped and 

 a new mouth and jaws were formed, their eyes 

 were turned upside down and inside out and 

 a new set of swimming organs had to be devel- 

 oped. 



According to the more orthodox view, the verte- 

 brates from their earliest stages stood in wide 

 contrast to the crustaceans, arachnids and insects. 



For while both groups comprise segmental animals, 



7 



