380 



THE EVOLUTION OF THE METAZOA 



the groups of Coelenterata indicated as a side branch so that 

 finally we still get the impression of a bifurcation where the 

 actual stem is represented by one of the two branches. The 

 point in question is here a common, very primitive and perhaps 

 planuloid ancestral form. Schmalhausen also goes his own 



VERTEBRA! A 



ACEPHALA CyCLOSTOMATA 



\\\y 

 CHORDONIA 

 prima ACEPHALA INSECJA 



BRACHIOPODA 



ENTEROPNEUSTA 

 ECHINODERMA 



TENTACULATA 



BRYOZOA 



NEMERTINEA 



NEMATOMORPHA 



TURBELLARIA 



TREMATODE5 

 CESTODES 



MYRIAPODA 

 / ARACHNOIDEA 



ONYCHOPHORA yfxiPHOSURA 



TR ACHE AT A y> GIGANTOSTRACA 



POLYCHAETA x p,,^,, ^,/^ CRUSTACEA 



OUGOCHAETaX II CRUSTACEA 



HIRUDINEA^.^ II y pnm,7. 

 VERMES 



POLY MERE A 

 MOLLUSCA 



VERMES 



primil. 



(BILATERIA) 



INFUSORIA 

 FLAGELLATA 

 SARCODINA 

 ■SPOROZOA 



CTENOPHORA 



ANTHOZOA 



SCYPHOMEDUSAE 



HYDROIDA 



COELENTERATA 



.SPONGIAE 



Fig. 52. Genealogical tree of animal kingdom. (After Schmal- 

 hausen.) 



way in his interpretation of the phyletic conditions of the 

 Bilateria; later we will return to this problem. 



A very interesting suggestion was made by G. S. Carter 

 (1940:482; cf. Fig. 53). In his construction of the genealogical 

 tree Carter takes into account to a considerable degree the 

 conditions that can be observed in larvae. We have already 

 declared such a method erroneous. The classification of the 

 animal world as it was proposed by Carter shows consider- 

 able simplifications which certainly is a welcome sign even 



