THE NEW GENEALOGICAL TREE 



381 



if Carter goes in my opinion a little too far. Carter 

 divides the Aletazoa (these are actually the Eumetazoa, they 

 do not include the' Spongiae as the Parazoa) at their very 

 root ("the ancestral metazoan") into two lines; these two 

 stems were given the rank of superphyla, they are very 



ANNELID 



superPhylum 



ECHINODERM 

 SUPERPHYLUM 



7COELENTERATA 



ANCESTRAL 

 METAZOAN 



Fig. 53. "Evolutionary relationship of the invertebrate phyla" 

 by G.S. Carter. 



unequal, and they corespond roughly to the dichotomy Proto- 

 stomia : Deuterostomia (the "Annelid superphylum" and the 

 "Echinoderm superphylum"). As regards the Coelenterata 

 Carter remains undecided; nevertheless he shows an inclination 

 to derive them as an independent stem or as a third branch 

 from the same "ancestral metazoan." A definite progress can 

 be seen in his idea of a hypothetical ancestral form which had 

 lived as a benthonic animal and was as such bilaterally sym- 

 metric, which had three body layers and did not consist of 

 metameres (the amerous state), which showed a slight 



