SOME CONSEQUENCES OF EVOLUTIONARY RELATIONSHIP 



363 



Blastulo Stage 



Gastru 



rip 



ob 



a Stage 



astic 



Coelom, Tubular 

 Digestive Tract, 

 Circu atory Syst. 



Somites 



^_ 



Dorsal Nerve Cord 

 Notochord, etc. 



Zygotes 



-X Protozoa 



-X Colonial Protozoa 



-X Sponges 



-X Coelenterata 



-'< 



Comb Jellies 

 Flatworms 



-X 



Molluscs 

 Echinoids, etc. 



■X Amphioxus 



Backbone, etc. 



Ventral Nerve Cord 

 Segmental Append- 

 ages, etc. 



Further 

 Modifications 



-X Fishes 



Further 

 Modifications 



X 

 Annelids 



/ 



-X 



Other 

 Vertebrates 



X X 



Arthropods 



Fig. 24.6. Diagram illustrating parallelism and recapitulation in embryonic development. 



