ECHIN0DE1UIATA. 



59 



body of the larva is converted into the substance of the perfect 

 animal ; the rest is either absorbed by the growing animal, or 

 shrivels up and disappears. 



Below the twelve models in Case b may be seen a representation 



Fiar. 39. 



Pentacrinoid stage of Antedon rosacea, 

 a, arms ; b, basals ; r, radials ; s, stalk. 



of three stages in the history of the Feather-star (Antedon rosacea). 

 The larvae of this Echinoderm are not free, but are attached by a 

 stalk; in the common Feather-star and other Comatulida. the stalk 

 is found during larval stages only ; in others, such as Pentacrinus, 

 it persists throughout life. 



F 



