THE WEALTH OF LIFE 



11 



the several branches, the student has made one of the 

 most important steps in the study of animal life. Much 



FIG. 2. GENEALOGICAL TREE. 



The small branches in the centre indicate the classes of " worms " ; the 

 letters P, B, and S indicate the positions of Peripatus, Balanoglossus, and 

 Sphenodon or Hatteria respectively. 



