IX 



PHYLUM ECHINODERMATA 



431 



opens. A smaller adored band (aor) in the interior of the 

 mouth has the function of attracting nutrient particles. The 



FIG. 343. Diagrams of the development of the larvre of Echinoderms. 1, Primitive form of 

 Echinoderm larva ; 2 and 3, Development of an auricularia (Holothuroidea) ; 4, 5, and <>, 

 Development of a Inpinnaria (Asteroidea) ; 7, 8, and 9, Development of a pluteus (Echinoidea 

 and Ophiuroidea). aor. adoral band of cilia ; all. alimentary canal ; an. anus ; b, b. processes 

 or arms; mo. mouth; por. peri-oral ciliated band and processes. (From Leuckart and 

 Nitsche's Diagrams.) 



peri-oral band undergoes characteristic changes in the different 

 classes, and the form of the larva at the same time becomes 



