CAKE-URCHIN. 



181 



it is protected by five groups of spines projecting over it, 

 as in a Starfish. Within these are teeth. The inside of 

 the Cake-Urchin is curiously strengthened by irregular 

 calcareous processes or plates; and the spines, which are 

 very minute, are nearly similar in structure to those of 

 the Spatangi. 



The vignette represents a magnified view of a spine, 

 and of a portion of the surface, showing the arrangement 

 of the granules. 



