MONOGRAPH OF THE EXISTING CRINOIDS. 165 



Thus in the asteroids \ve know that tho terminals at tin- end of the arms are rcallv 

 body plates pushed outward by the growth of the arms and by the addition of new 

 plates just beneath them. And similarly we are equally sure that in the echiuoids 



FIG. 103. LATERAL VIEW OF A SPECIMEN OF ANTEIWIN PETASI-S FROM SWEDEN, SHOWING THE RELATIVE PROPORTIONS OF THE 



ARMS, PINNULES, CENTRODORSAL AND CIRRI. 



the primitive position of the coronal ring is around the mouth, it having been shoved 

 to a position about the poriproct by the entire growth of the body having been 

 ventralward, just as it is outward in the asteroid arm, forming new plates as it 

 goes. 



