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 



Fm. 116. Larvae of Antedon (after Thomson), a free-swimming 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 



