Invertebrata. 



appearance these Crinoids look like star-fishes fixed on 

 central jointed stalks, and they are furnished with 

 feathery ambulacral feet on their upper surface, which 

 as they cannot serve for locomotion seem to act as gills 

 for breathing. The commonest of the living Crinoids 



FIG. 29. 



Embryo of the Feather Star, 

 showing its stalked, encFi- 

 nite-like stage. 



Rosy Feather Star (Antedon 

 fosaceus), adult or free con- 

 dition. 



becomes free in its adult stage, and has a singular his- 

 tory. Beginning its life as a free- swimming embryo, 

 it soon becomes fixed, and appears as a stalked orga- 

 nism (fig. 28), but, after existing in this state for a 

 short period it loses its attachment, becomes free, 

 and forms the exquisitely tinted rosy feather star, with 

 ten to forty arms, found in our seas. 



CLASS II. Starfishes (Stellerida), (fig. 3, p. 7). 

 The form of the animals of this class is expressed by 



