PREFACE. 



XV n 



to place the" work in tlie hands of the students of my own classes, I need 

 not apologise for adding here further details of the classification which I 

 find it most convenient to adopt in teaching. I have arranged the chief 

 phyla first of all in the form of a genealogical tree, and secondly in a 

 series exhibiting their subdivisions into classes, etc. This classification is 

 of course to a large extent only a modification and adaptation of systems 

 already put forward by other naturalists. 



c3 



^ 





^ 



u 

 o 



o 





C3 



O 







a 

 o 





e3 

 o 



ta 



C3 



d 

 bo 

 o 





e3 



§ 

 o 



e3 



13 



S 

 ID 



Grade II. CCELOMATA. 





Grade I. CCELENTERA. 

 Grade II. ENTEROZOA. 



C3 

 O 



C3 

 O 



O 

 S-l 



P4 



Grade I. PLASTIDOZOA. 



