NOTES ON ECHINODEKM MORPHOLOGY. 23 



" basal/' in brackets, after " Dorsocentral/' ^ in the explana- 

 tory description of a copy of Loven's figure of a young 

 Asterias glacialis. I have pointed out more than once, and 

 Sladen has expressed the same views, that it is impossible to 

 arrive at a rational morphology of the Echinoderm apical sys- 

 tenl, if a primitively single plate " Centrale " is to be considered 

 as homologous with five peripheral ones, whether they be radial 

 or interradial, under-basals or basals. 



1 " Atlas," p. 27. 



