DEVELOPMENT OF ANTEDON. 



159 



acquires a water-pore and sand-canal which lead from their 

 first appearance into the general body cavity. 



The genital stolon (axial organ) develops as a thickening in 



FlO. 116. Larvae of Antedon (after Thomson), a free-swimrning larva with rings of cilia; 

 b attached cystid stage ; c older stage described as Pentacrinus europaeus with arms and 

 cirri. 



the epithelial wall of the aboral coelom. The genital rachis is 

 probably developed as an outgrowth of this. 



The larva becomes converted into the pentacrinoid larva 



