134 



BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Spicules and plates of what is probably the primitive type persist in many of the 

 holothurians, and are developed in certain situations in species of all the other 

 classes, in the crinoids making up the visceral, and most of the perisomic, skeleton. 



FIG. 81. DORSAL VIEW OF THE CENTRAL STRUCTURES AND OF A SINGLE POST-RADIAL SERIES OF A SPECIMEN OF COMANTHUS 

 SOLASTER FROM SOUTHERN JAPAN, SHOTTING THE RELATIVE PROPORTIONS OF THE VARIOUS PARTS. 



These spicules are in general suggestive of the spicules of certain sponges and 

 alcyonarians, both in form and in origin, and it is in the skeletons of these animals 

 that the skeleton of the echinoderms, though entirely independent in origin, finds 

 its nearest counterpart. 



